The Global Minimum Tax Implementation Toolkit (EN)

Global Minimum Tax Implementation Toolkit

This work was approved and declassified by the OECD Committee on Fiscal Affairs on 22 April 2026.

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Please cite this publication as: OECD (2026), The Global Minimum Tax Implementation Toolkit, OECD Forum on Tax Administration, OECD Publishing, Paris, https://doi.org/10.1787/0ee66d84-en.

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Acknowledgments

The project was funded by the European Union via the Technical Support Instrument, and implemented by the OECD, in co-operation with the European Commission. The work also benefited from financial support by other contributors.

Table of contents

Acknowledgments 3

Introduction 6

Module 1. Assessing in-scope MNE groups and revenue 12

Introduction 12 1.1. Using CbC reports to estimate the population of in-scope MNE Groups in a jurisdiction 13 1.2. Commercial datasets 20 1.3. Other sources of data to estimate in-scope population 24 1.4. Estimating top-up tax revenue 28

Module 2. Legal Implementation 34

Introduction 34 2.1. Legislative techniques 36 2.2 Legislative techniques for updating domestic law 42 2.3. Interpretation mechanisms 46

Module 3. Organising and Planning for the Implementation of the GMT 49

Introduction 49 3.1. Implementation plan 49 3.2. Assessing key tax administration functions and need for changes 51

Module 4. Framework on Compliance Procedures 68

Introduction 68 4.1 GMT Compliance procedures and best practices 69

Module 5. Exchange of Information 85

Introduction 85 5.1. Legal implementation of the exchange of information under the GloBE Rules 86 5.2. Operational implementation of exchange of information of the GIR 91

FIGURES

Figure 1. The GMT implementation roadmap 11 Figure 2. Applying filters to aggregated CbC reporting data in the OECD Data Explorer 25 Figure 3. Estimating the number of in-scope MNE groups by UPE jurisdiction using aggregated CbC reporting data 26

Figure 4. Calculation of top-up taxes under GloBE Figure 5. External communication objectives and channels 60 Figure 6. IT Functionalities for GMT Compliance 61 Figure 7. Key Steps of the GMT Compliance Procedures 69

TABLES

Table 1. Ownership data from Orbis is relatively complete 21 Table 2. Key data scenarios and recommended data sources 29 Table 3. Comparison of ambulatory and static approach of cross-reference 39 Table 4. Overview of the key tax administration functions 52 Table 5. Dissemination approach for the General Section 94 Table 6. Dissemination approach for the Jurisdictional Section(s) 95

Introduction

1. The Global Minimum Tax (GMT) agreed in 2021 by the Inclusive Framework on BEPS (IF) consists of a coordinated set of rules - the Global Anti-Base Erosion (GloBE) Rules¹, as complemented by a Commentary and Administrative Guidance² - designed to ensure that large multinational enterprises (MNE) are subject to a minimum level of tax in each jurisdiction where they operate. Where the level of tax is below the agreed minimum, the top-up tax is either collected by the low-tax jurisdiction itself, under a so called Qualified Domestic Minimum Top-up Tax (QDMTT), or, where no QDMTT applies, by another implementing jurisdiction through the imposition of either: a. an Income Inclusion Rule (IIR) which imposes top-up tax on a parent entity in respect of the low taxed income of a constituent entity; or b. a UTPR which denies deductions or requires an equivalent adjustment in a subsidiary jurisdiction in order to produce an equivalent incremental increase on the taxes paid by the MNE Group.

2. The rules also include agreed safe harbours that provide relief either by means of simplification or deemed top-up tax of zero in a given jurisdiction to the MNE Groups when conditions for specific safe harbour are met. Jurisdictions deciding to adopt these rules – in whole or in part – implement them in their domestic law and, in doing so, recognise the safe harbours and the qualified GMT rules of other jurisdictions in line with the agreed rule order.³

3. To date, over 60 jurisdictions have already implemented the rules, while many others are in the process of evaluating or preparing for implementation. While the domestic tax system of each implementing jurisdictions may differ, many implementing jurisdictions have confronted similar issues when transposing the GMT into their tax system. The existence of common challenges highlights the benefits from common and coordinated approaches. These shared challenges and opportunities were first acknowledged by the Forum on Tax Administration through the Large Business International Programme (LBIP) which extended an invitation to tax administrations from Inclusive Framework countries to a kick-off event in Amsterdam in October 2024 to discuss GMT implementation and compliance issues. The event was open to all IF members and attended by close to 70 tax administrations, along with business, 1 For further details on the GloBE Rules, see: https://www.oecd.org/en/topics/sub-issues/global-minimum-tax/globalanti-base-erosion-model-rules-pillar-two.html 2 OECD (2025), Tax Challenges Arising from the Digitalisation of the Economy – Consolidated Commentary to the Global Anti-Base Erosion Model Rules (2025): Inclusive Framework on BEPS, OECD/G20 Base Erosion and Profit Shifting Project, OECD Publishing, Paris, https://doi.org/10.1787/a551b351-en; https://www.oecd.org/en/topics/subissues/global-minimum-tax/global-anti-base-erosion-model-rules-pillar-two.html#administrative-guidance. 3 The rule order entails that the application of the GMT rules in one jurisdiction (say the IIR in the jurisdiction of a Parent Entity) is deactivated where they are qualified GMT rules applicable in another jurisdiction that take priority (say the QDMTT Safe Harbour in the jurisdiction of the low-taxed Entity). To achieve this outcome, each implementing jurisdiction need to have a common transparent basis for recognising qualified rules in another jurisdiction in a timely fashion. academics and other stakeholders. The participants at this meeting emphasised the importance of increased and continued dialogue and collaboration on compliance approaches that deliver on the policy goals of the GMT in a way that minimises compliance cost and complexity for both taxpayers and tax administrations.

4. Following this meeting, the FTA endorsed the idea of a structured dialogue through the LBIP that would engage with IF members and seek inputs from external stakeholders (hereafter, the “Amsterdam Dialogue”). While all IF members were invited to input into the discussions, the dialogue focussed on three priority areas of particular interest to implementing jurisdictions: (i) upfront compliance, (ii) co-ordinated risk assessment, including systems-based approaches where appropriate, and (iii) dispute prevention and resolution. In addition, discussions emphasised the importance of ensuring tax certainty and consistency while reducing compliance burdens so to help jurisdictions that are implementing the GMT. The FTA agreed to continue the Amsterdam Dialogue to advance on these goals and endorsed the delivery of a common framework on upfront compliance as well as development of a co-ordinated risk assessment framework to support consistent, risk-based and effective implementation.⁴

5. The Global Minimum Tax Implementation Toolkit (the “Toolkit”) addresses the first of these two aspects. Its objective is to assist jurisdictions that have already implemented the rules or have decided to implement the rules with establishing a robust and efficient domestic compliance framework – the combination of rules, procedures, and practices that support the collection and enforcement of the top-up tax, including IT systems as well as practical and organisational considerations. It draws on the experiences of those jurisdictions further advanced in the implementation journey, includes input from the business and wider stakeholder community and seeks to identify best practices. These best practices are meant to serve as guidelines for implementing jurisdictions in the design their administrative framework and not to set standards. This Toolkit is an important element within the wider approach designed to deliver on the status of the GloBE rules as a common approach. The concept of the common approach is intended to ensure that those jurisdictions that proceed with implementation do so in a way that brings consistency and coordination in the application of the rules across different jurisdictions. At the same time these best practices have primarily been drawn from jurisdictions that were early adopters of the GMT and may not always translate into the specific context of all implementing jurisdictions, particularly those of developing countries.⁵

6. As part of the wider efforts to ensure consistency and coordination in the application of the GloBE Rules across different jurisdictions, the IF agreed to establish a peer review process. This process provides a common framework for assessing and recognising the “qualified” status of the IIR, UTPR and/or QDMTT (including eligibility for the QDMTT Safe Harbour), based on a full legislative review and an 4 Statement of outcomes: Forum on Tax Administration Plenary

   1. https://www.oecd.org/content/dam/oecd/en/events/2025/11/forum-on-tax-administration-2025-event/statement-of-

   outcomes-fta-plenary-meeting-2025.pdf. 5 The OECD has developed an extensive capacity building programme to support developing countries in understanding the GloBE rules, how they interact with existing tax incentives, and in analysing the appropriate policy choices in the context of a comprehensive programme of support on international tax (see https://www.oecd.org/en/topics/tax-and-development.html for an overview of the OECD’s work on tax and development). The OECD’s Global Relations Programme on Tax (https://www.oecd.org/en/about/programmes/globalrelations-programme-on-taxation.html) provides in-person and virtual multilateral training, recorded webinars and selfpaced e-learning resources on the GloBE rules. Bilateral assistance to support implementation of the GloBE rules is also available through the OECD/UNDP Tax Inspectors Without Borders initiative (https://www.tiwb.org). To assist tax policy and administration officials with considering whether or not to adopt the GMT, including assessing different implementation options, a separate Implementation Handbook is available (see OECD (2023), Minimum Tax Implementation Handbook (Pillar Two), OECD/G20 Base Erosion and Profit Shifting Project, OECD, Paris, https://www.oecd.org/tax/beps/minimum-tax-implementation-handbook-pillar-two.pdf). ongoing monitoring process of each jurisdiction that implements the GMT.⁶ In addition, the IF has adopted a transitional mechanism allowing the timely recognition of the qualified status of an implementing jurisdiction’s legislation on a temporary basis. This transitional approach relies on self-certification by the implementing jurisdiction, supported by a high-level review of its domestic legislation. Jurisdictions that qualify under this process are then recorded in a central record of jurisdictions with qualified status. This central record is maintained and regularly updated on the OECD website.⁷ A central record of qualified rules provides certainty to MNE Groups and reduces risks of double or over-taxation while allowing time for the full legislative review to be undertaken.

7. In parallel, the IF has also taken several initiatives to support a consistent and coordinated approach to the administration of the GMT rules, particularly in relation to the collection and exchange of taxpayer information. Key initiatives include: • Common rules for the collection of GloBE information through the GloBE Information Return (GIR)⁸. The GloBE rules impose, by default, on each Constituent Entity of an in-scope MNE Group, an obligation to file the GIR with the tax administration of the jurisdiction where it is located. This local filing obligation, however, is switched off if the GIR is centrally filed in the jurisdiction of the Ultimate Parent Entity (UPE) or the Designated Filing Entity (DFE) and the Competent Authority of that jurisdiction has entered into a bilateral or multilateral agreement or arrangement in effect to automatically exchange the GIR with the Competent Authority of the jurisdiction of another Constituent Entity. • The standardised template for the GIR released in July 2023, and updated in January 2025,⁹ which has been designed to provide each implementing jurisdiction with access to the information they need to perform an appropriate risk assessment and to verify the calculation of an MNE Group’s GMT liability in a given jurisdiction. The GIR template specifies all data elements necessary to verify the correctness of a GMT liability, specific rules ensuring that each jurisdiction receives only the portions of the GIR that is relevant for the application of their own GMT rules, consistent with the MNE Group’s structure, the rule order and the agreed dissemination approach.¹⁰ • The Multilateral Competent Authority Agreement on the Exchange of GloBE Information (GIR MCAA) released in January 2025.¹¹ The GIR MCAA provides a framework for the central 6 The legislative review will determine if the legislation of an implementing jurisdiction achieves consistent outcomes with those provided for under the GloBE Rules. The ongoing monitoring will review if the rules are being applied and administered consistently with the GloBE Rules, and that an implementing jurisdiction does not provide benefits which are related to the GloBE Rules. The terms of references that will serve as a basis for these reviews are currently under development. 7 See: https://www.oecd.org/en/topics/sub-issues/global-minimum-tax/central-record-of-legislation-with-transitionalqualified-status.html 8 As provided for Article 8 of the MR, released in 2021. 9 OECD (2025), Tax Challenges Arising from the Digitalisation of the Economy – GloBE Information Return (January 2025): Inclusive Framework on BEPS, OECD/G20 Base Erosion and Profit Shifting Project, OECD Publishing, Paris, https://doi.org/10.1787/a05ec99a-en. Note that the standardised template for the GIR may be modified in the future to accommodate future changes agreed by the IF members. 10 The dissemination approach agreed by the IF ensures that implementing jurisdictions can collect or access the information they need depending on their specific situation in relation to each MNE Group that is subject to the rules in their jurisdiction. 11 OECD (2025), Tax Challenges Arising from the Digitalisation of the Economy – Multilateral Competent Authority Agreement on the Exchange of GloBE Information (January 2025), OECD/G20 Inclusive Framework on BEPS, OECD, filing of the GIR with a single tax administration and the subsequent exchange with the other tax administrations. It sets out the detailed modalities for the exchange to take place on an automatic basis, including the confidentiality and data safeguards that must be respected.¹² A list of the jurisdictions that signed the GIR MCAA is available on the OECD website.¹³ As an alternative, jurisdictions may also conclude a bilateral Competent Authority Agreement that is based on the Convention, a Tax Information Exchange Agreement, a Tax Treaty with a provision equivalent to Article 26 of the OECD Model Tax Convention or any other international agreement that allows automatic exchange of information. • The GIR XML Schema and corresponding User Guide released in January 2025 to support the automatic exchange of the GIR between tax administrations.¹⁴ This XML Schema translates the GIR standardised template into a common schema of extensible mark-up language to allow for this information to be reported and exchanged in a single Information Technology (IT)-format. Designed primarily to facilitate exchange of the GIR when filed centrally in the jurisdiction of the UPE or DFE of the MNE Group, it is also intended to be used to facilitate the local filing of the GIR. • The GIR Status Message XML Schema (incl. common validation rules) released in July 2025¹⁵ to improve the quality and consistency of data exchanged through the GIR XML Schema. Since the data transmitted via the XML Schema may contain errors, such as those arising from incorrect file preparation or incomplete or inaccurate records, the common status message XML is a template allowing tax administrations to report such errors in a structured manner to the sending tax administration. It can also be used by a tax administration to provide a status message to its domestic filing Constituent Entities. It also includes the list of agreed file and record validation rules to be checked for the purpose of identifying errors in the GIR filing. These initiatives are standards agreed by the IF that together form the basis of the common approach. The work undertaken in the context of the Amsterdam Dialogue does not impact on these standards. Rather, it seeks to assist tax administrations with applying these standards in a consistent and co-ordinated way.

The Global Minimum Tax Implementation Toolkit

1. Once a jurisdiction has made a decision to adopt all or part of the GMT, the subsequent steps required to implement the domestic rules and prepare for their effective administration are specific to each implementing jurisdiction. While the content of the implementation will necessarily be specific to each jurisdiction, and tailored to its needs, its development generally relies on assessments and methods that are common across several jurisdictions. At the same time, experience shared through the Amsterdam Dialogue shows that tax administrations face many of the same challenges when integrating the GMT into their domestic compliance framework and preparing for the first filing requirements and payment deadlines. The discussions in the Amsterdam Dialogue underlined the value of developing common guidelines and best practices to support tax administrations in this process, which Paris, https://www.oecd.org/content/dam/oecd/en/topics/policy-subissues/global-minimum-tax/multilateralcompetent-authority-agreement-exchange-of-globeinformation.pdf. 12 The GIR MCAA is based on Article 6 of the Convention on Mutual Administrative Assistance in Tax Matters (the Convention). 13 See the public record of the signatories list : https://www.oecd.org/content/dam/oecd/en/topics/policy-issues/taxtransparency-and-international-co-operation/gir-mcaa-signatories.pdf 14 OECD (2025), GloBE Information Return (Pillar Two) XML Schema: User Guide for Tax Administrations, OECD Publishing, Paris, https://doi.org/10.1787/c594935a-en. 15 OECD (2025), GloBE Information Return (Pillar Two) Status Message XML Schema: User Guide for Tax Administrations, OECD Publishing, Paris, https://doi.org/10.1787/449e3cc3-en. • draw on the practical experience of early adopters; • clarify key aspects of the GMT implementation for tax administrations, including timelines and milestones; • help identify and address common challenges; and • promote consistency and coordination across jurisdictions through best practices, thereby reducing compliance and administrative burden for both tax administrations and taxpayers.

2. In response to this need, the Toolkit has been structured as a roadmap setting out the key steps and actions that tax administrations commonly undertake to implement the GMT. This roadmap is intended to serve as a model and practical reference guide that tax administrations can adapt to their specific legal, administrative, and operational contexts. To help with organisational aspects and clarify possible timelines, the Toolkit is structured around an implementation roadmap broken down into two phases: • A pre-Implementation phase - Once a jurisdiction has decided to adopt all or part of the GMT, the first step for the tax administration is usually to assess and identify what changes and new features are needed to establish a robust and efficient compliance framework ahead of the first filing and payment deadlines.¹⁶ This is a planning exercise that typically involves: o Estimating the number of in-scope MNEs and potential revenue (Module 1); and o Assessing the implications of how the GMT is (or will be) incorporated into domestic legislation (Module 2). • An implementation phase - Building on the GMT implementation choices, the next step for the tax administration is usually to execute its different elements so that the compliance framework is fully operational by the first filing and payment deadlines. This usually involves: o Developing a GMT implementation plan with a timeline, costs, budget, introducing organisational and IT changes, and rolling out a communication strategy (Module 3); o Designing and operationalising compliance procedures that support collection of the top-up tax (Module 4); and o Leveraging opportunities offered by international cooperation in order to receive the necessary information to risk assess the top-up tax due, in particular the automatic exchange of the GIR (Module 5).

3. The Toolkit seeks to provide a comprehensive description of the GMT implementation process that is usually carried out by tax administrations, spanning from the initial assessment of impact and legal implementation of the rules to the collection and administration of the top-up tax (see below Figure 1). 16 In some jurisdictions, tax administrations are also involved in the legislative process that leads to the incorporation of the GMT rules into domestic legislation. This role however varies significantly across jurisdictions, including in some jurisdictions no or a very limited role for tax administrations.

Figure 1. The GMT implementation roadmap

1. The Toolkit is broken down into separate (but complementary) modules, with each module dedicated to a specific stage of the implementation process. This modular approach should allow tax administrations to use the Toolkit in a way that best fits their context and needs, including where relevant by using only selected modules independently from the others.

2. It is intended for use by tax administration and tax policy officials but could also be useful for other stakeholders involved in the application of the GMT rules. While this Toolkit builds on the GloBE Model Rules and other standards agreed by the IF, it does not interpret or modify the application or interpretation of these standards and the guidelines set out in this toolkit should only be used and applied in a manner consistent with those standards.

3. The Toolkit may undergo occasional updates to reflect further progress and findings, as implementing jurisdictions continue to gain more experience from the application of (and compliance with) the GMT rules. It does not cover ongoing work with respect to risk assessment and verification approaches nor coordination mechanism for addressing potential disputes.

Key observations on assessing in-scope MNE Groups and revenue estimates

Based on the discussions held in the context of the Amsterdam Dialogue, this Toolkit includes the following key observations on assessing in-scope MNE Groups and revenue estimates for GMT implementation: • CbC reports are best suited to estimating in-scope taxpayers for upfront compliance, subject to the requirement for the appropriate use of CbC reporting data set out in the BEPS Action 13 report. • However, some jurisdictions may wish to use commercial data to validate identification of in-scope MNE Groups using CbC reports, or as an alternative if CbC reporting data is not available. • If neither CbC reports nor commercial data are available, further alternatives for assessing in-scope MNE Groups include using existing tax administration information, aggregated CbC reporting data published by the OECD or a registration procedure for in-scope MNE Groups. • Information on the identified in-scope MNE Groups can be used for top-up tax estimates as part of an economic impact assessment. • Details of key steps and adjustments in forthcoming OECD-World Bank document: “Estimating QDMTT revenue using firm-level data: a practical guide”.

Introduction

1. This module provides considerations and recommendations on identification of in-scope MNE groups and assessment of GMT revenue. Where a jurisdiction includes wholly domestic groups within the scope of its GMT rules, the content of this module may also be applied to identify these in-scope groups with appropriate adjustments (e.g. a wholly domestic group will not be required to prepare and file a country-by-country (CbC) report).

2. When a jurisdiction is in the process of introducing the GMT there are a number of benefits in having a reasonably accurate estimate of the population of MNE Groups that are likely to be in scope of rules in that jurisdiction. First, the GMT requires an infrastructure for the receipt and handling of GIRs that needs to be designed and implemented or adapted from that which currently exists. Other modules in this Toolkit cover different elements of this infrastructure, but across all of these elements an understanding of the likely scale of the in-scope population is important to ensure the readiness of the tax administration in advance of the first filing deadline.

3. Second, a broad understanding of the MNE groups that are most likely to be subject to the GMT will help a tax administration in communicating with in-scope entities to promote an awareness of their

Module 1. Assessing in-scope MNE

groups and revenue

obligations under the GMT (e.g. GMT filing and payment obligations/deadlines) and an understanding of how these can be met in that jurisdiction (e.g. the mechanics for how the GIR should be filed, or notification given where a GIR will be filed by another group member in a different jurisdiction). This can promote voluntary compliance with rules by ensuring local Constituent Entities in an MNE Group understand how the GMT will operate in their jurisdiction, as well as by putting a Constituent Entity on notice that the filing of a GIR is expected if the MNE Group is ultimately within the scope of rules for a period.

1. Third, an understanding of the likely in-scope population supports the estimation of the tax revenue that may be raised under the GMT. Identifying MNE Groups and entities likely to fall within the scope of the GMT represents an initial step in estimating potential GMT revenue using entity-level data. Subsequent steps involve estimating the amount and nature of low-taxed profits in a jurisdiction, estimating potential top-up tax revenue, and analysing the extent to which low-taxed outcomes are driven by the use of tax incentives. Estimating the potential tax revenue that is likely to be levied under the GMT can assist jurisdictions in evaluating likely impacts on their economies and in considering appropriate domestic policy responses.

2. However, while each of these drivers for an understanding of the in-scope population are important, they can all be achieved where a tax administration has a reasonably accurate estimate of that population. A precise knowledge of exactly which local taxpayers will and will not be members of MNE Groups that are in-scope of rules in advance may not be needed, and there may also be specific aspects of rules (e.g. concerning particular categories of Constituent Entities in MNE Groups) where a tax administration may consider it more efficient and effective to leave until after GIRs are filed in order to assess compliance in light of the additional data they provide. A tax administration should therefore consider how accurate an estimate is needed for its intended purpose, and weigh this against the additional burden on the tax administration itself from undertaking the process for a very detailed estimate and on MNE Groups if they are required to undertake any additional compliance steps.

3. Whether a tax administration determines it requires a detailed understanding of the specific MNE Groups likely to be in scope of the GMT in its jurisdiction, or only a high-level estimate of the size of the in-scope population, different data sources may be leveraged to achieve this. In particular, where a tax administration has access to CbC reports prepared and filed in accordance with BEPS Action 13, and/or reliable commercial datasets such as Orbis, these can be a valuable source of information, either used alone or together, and this module explores several ways in which this data can be used. However, data availability differs between jurisdictions, and where neither of these sources are available to a tax administration, there are other sources, such as aggregated CbC reporting data, consolidated financial statements and pre-filing registration requirements, that can be used which can still provide a useful estimate.

4. The estimation of potential top-up taxation is not covered here in detail but is discussed in a forthcoming paper (OECD-World Bank, forthcoming). This module also does not consider steps that may be taken by tax administrations after the GIR filing deadline to identify instances of non-compliance with GloBE rules, which will be covered in later work on a risk assessment framework for the GMT.

1.1. Using CbC reports to estimate the population of in-scope MNE Groups in a

jurisdiction

1. To date, CbC reports have been the source of data used most frequently by tax administrations when attempting to estimate the number of MNE Groups likely to be in scope of the GMT in their jurisdiction as well as to identify specific in-scope MNE Groups. This section considers the advantages of CbC reports as a source of data for this exercise, as well as a number of challenges that they pose. It also describes two approaches to the use of CbC reports that a tax administration can take, depending upon the level of detail and specificity required. 1.1.1. The advantages of using CbC reports

2. CbC reports offer a number of advantages as a data source for estimating the population of MNE Groups that are likely to be in scope of a jurisdictions GMT. Similarity in thresholds under BEPS Action 13 and Pillar 2

3. Both CbC reporting under BEPS Action 13 and the GMT apply a revenue threshold of EUR 750 million. Although differences in the application of these revenue thresholds mean that the population of in-scope MNE Groups for the GMT may not be precisely the same as those for CbC reporting (see section 1.1.2), in many cases if an MNE Group is in scope of CbC reporting it can be assumed it is reasonably likely that the MNE Group will also be in scope of the GMT for the same period without undertaking further work. This is particularly the case where a EUR-denominated threshold applies to the MNE Group for CbC reporting purposes. As such, using CbC reports to estimate an in-scope population can be a relatively straight-forward exercise. Approaches to undertake such an exercise, and some exceptions where further work could be needed to obtain a more precise estimate, are discussed below. Information on the Ultimate Parent Entity and the MNE Group’s reporting period contained in CbC reports

4. Where a particular MNE Group is considered likely to be in scope of the GMT based on its CbC reports, these CbC reports will also provide information on the MNE Group’s Ultimate Parent Entity (UPE), including where it is resident for tax purposes. This can be useful for the tax administration in another jurisdiction to understand which, if any, of its jurisdiction’s GMT rules may apply. For example, if the UPE is resident in a jurisdiction that applies a Qualified IIR, or if the Side-by-Side (SbS) Safe Harbour is available (which can quickly and easily be confirmed by cross-checking the jurisdiction where the UPE is resident against the published list of jurisdictions that have an eligible system), then an IIR or UTPR in other jurisdictions will not apply. On the other hand, if the UPE is resident in a jurisdiction that does not apply a QIIR, and that does not have an eligible system for the purposes of the (SbS) Safe Harbour, then local entities or Permanent Establishments (PEs) of the MNE Group resident in another jurisdiction could be subject to the IIR or UTPR in that jurisdiction, should the conditions for those rules to apply be met. All MNE Groups, including those subject to a QIIR or eligible for the SbS Safe Harbour, remain subject to the QDMTT in all QDMTT jurisdictions in which they operate.

5. The SbS Safe Harbour provides a mechanism for recognising cases when an MNE Group is headquartered in a jurisdiction with a tax system that imposes minimum tax requirements with respect to domestic and foreign income. The Safe Harbour operates to switch off the application of a jurisdiction’s IIR and UTPR where the UPE of an MNE group is located in a jurisdiction that has been listed in the Central Record as having met the conditions of an eligible regime.

6. An MNE Group’s CbC report also includes the reporting year end of the UPE of the group. This can be helpful in understanding when a GIR is due to be filed on an MNE Group, as under rules for the GMT this filing deadline is linked to the year-end of the UPE of the MNE Group, which may be different to year-end of entities in the tax administration’s jurisdiction.

7. It is important to note, however, that since all of this information is derived from prior-year CbC reports, it may not be fully accurate (e.g. if there have been subsequent changes to the MNE Group) but would still be useful for a tax administration’s planning purposes. Information on local Constituent Entities

8. In addition to providing information on the UPE of an MNE Group, the CbC reports of an MNE Group likely to be in-scope of the GMT will also provide information on the MNE Group’s Constituent Entities in each jurisdiction where it has operations. This is useful for the purposes of determining which local entities or PEs may be subject to the GMT in a particular jurisdiction (i.e. those in the jurisdiction of the tax administration undertaking the review). Ease of availability of CbC reports in many jurisdictions

9. CbC reporting has been widely adopted by members of the IF. As of April 2026, over 120 IF members require the filing of CbC reports and almost 90 are in a position to receive CbC reports on foreignheaded MNE Groups through the automatic exchange of information. This means that substantially all large MNE Groups are covered by a CbC reporting filing obligation and these reports are available to the majority of jurisdictions that are currently in the process of implementing the GMT. 1.1.2. Limitations and challenges in using CbC reports

10. While CbC reports offer a number of benefits as a source of data for estimating the population of MNE Groups in scope of the GMT, they are also subject to a number of limitations and challenges, described below. The extent to which these limitations and challenges are relevant in a particular case will vary depending upon the jurisdiction relying upon the data and the profile of potential in-scope MNE Groups in that jurisdiction. The appropriate use of CbC reports

11. Under BEPS Action 13, CbC reports may only be used for the purposes of a high-level transfer pricing risk assessment, for the assessment of other BEPS-related risks, and for economic and statistical analysis, where appropriate. This does not restrict the ability of a tax administration to use CbC reports to undertake an economic analysis to estimate the likely in-scope population of in-scope MNE Groups in its jurisdiction, nor to undertake an initial risk assessment as to whether a particular MNE Group is likely to be in-scope for a specific period. However, a tax administration should not use CbC reporting data as conclusive evidence that an MNE Group or Constituent Entity is in-scope of the GMT, to require the filing of a GIR or the payment of top-up taxes, or to impose penalties in the event of non-filing or non-payment. Future work on a risk assessment framework for the GMT will consider steps that may be taken by a tax administration to determine whether a particular MNE Group should have filed a GIR in circumstances where no GIR was filed.

Differences in non-EUR denominated thresholds due to exchange rate movements

1. While Action 13 and Pillar 2 establish a common threshold of EUR 750 million, the two standards differ in the way in which non-EUR denominated thresholds are set by jurisdictions that wish to apply a threshold denominated in their local or other relevant currency. Specifically, under Action 13 a non-EUR denominated threshold must be equivalent to EUR 750 million as at January 2015. On the other hand, under Pillar 2, a non-EUR threshold must be re-based each year based on the exchange rate in December of the relevant year.¹⁷ 17 Paragraph 19 of the Commentary to the Model Rules provides that, for the purposes of applying the thresholds for GIR filing, jurisdictions should rebase their non-Euro denominated thresholds annually, based on the average foreign exchange rate for the month of December determined by the foreign exchange reference rates as quoted by the European Central Bank (ECB). Where this is not possible the jurisdiction should rebase their non-Euro denominated

2. In practice, this means that the CbC reporting threshold and the GMT threshold are likely to differ wherever the UPE of an MNE Group is resident in a jurisdiction that applies non-EUR denominated thresholds, and the extent of this difference may change from year to year depending upon current exchange rates. As such, there may be cases where a currency has depreciated against the euro meaning that some MNE Groups are required to file a CbC report that may not be subject to the GMT, or conversely a currency has appreciated against the euro meaning that some MNE Groups that are not required to file CbC reports may still be subject to the GMT.

3. A jurisdiction that is using CbC reports as a source of data can estimate how much of an issue this is likely to be by: • identifying the jurisdictions in which the greatest number of CbC reports they receive (or used to receive) are filed, including their own jurisdiction), and • where these jurisdictions apply a non-EUR denominated CbC reporting threshold, considering how much the currency of that threshold has moved against the euro since January 2015.

4. Where a jurisdiction has access to CbC reports, this difference in the applicable non-EUR denominated thresholds for CbC reporting and the GMT is probably the biggest single limitation on the use of this CbC reporting data for the purposes of estimating a population. The impact of Excluded Entities

5. Article 1.5 of the Model Rules identifies a number of Excluded Entities that will not be subject to the GMT. However, the fact that a Constituent Entity is an Excluded Entity does not prevent other members of their MNE Group from being subject to the GMT, unless they also meet the definition of an Excluded Entity. BEPS Action 13 on the other hand does not provide for special treatment of Excluded Entities and has no equivalent provisions for the purposes of CbC reporting. This means that a Constituent Entity that is an Excluded Entity for the GMT will still be included in a CbC report, even where the Excluded Entity is outside the charge to taxation under the GloBE rules.

6. The presence of an Excluded Entity in an MNE Group should not impact the usefulness of CbC reports for the purposes of estimating the population of in-scope MNE Groups in a jurisdiction, unless the only Constituent Entity in a particular jurisdiction is an Excluded Entity. However, the fact that a CbC report does not include any indication that the UPE or a Constituent Entity is an Excluded Entity may lead a tax administration to draw a conclusion that a taxpayer in its jurisdiction may be subject to the GMT when this is not the case. To address this, additional information to identify possible Excluded Entities may be needed. In practice, the likely number of Excluded Entities in most jurisdictions means that, even if a tax administration does not manage to anticipate all of them, this is unlikely to significantly impact the number of Constituent Entities expected to be subject to the GMT in a jurisdiction. Therefore, it is advisable that it may be more efficient and effective for a tax administration to wait until after the relevant filing and exchange deadlines, and undertake a risk assessment at that time to detect possible non-compliance, if needed. Partially Owned Parent Entities (POPEs), Minority Owned Constituent Entities (MOCEs) and Joint Ventures

7. Pillar 2 also includes specific rules on other particular types of entity that are not wholly-owned subsidiaries, namely: • Partially Owned Parent Entities (POPEs), thresholds based on the average foreign exchange rate for the month of December as quoted by the jurisdiction’s Central Bank. • Minority Owned Constituent Entities (MOCEs), and • Joint Ventures.

8. POPES and MOCES are controlled by the UPE of the MNE Group and so will be included in a CbC report prepared in accordance with Action 13. However, as the CbC report does not include an MNE Group’s group structure nor any information on cases where third parties hold ownership interests in a Constituent Entity, it will not be possible to identify a POPE or MOCE based solely on the contents of a CbC report.

9. This fact does not reduce the usefulness of CbC reports in estimating the population of MNE Groups in scope of the GMT in a jurisdiction, but it does mean that additional information is needed in order to determine whether the special rules applicable to POPEs and MOCEs apply. However, for the purposes of estimating the in-scope population, this determination is not necessary. Therefore, it is advisable that a tax administration wait until the GIR is received in order to undertake a risk assessment on the correct application of these rules, if needed.

10. Joint Ventures are jointly owned entities that are not controlled by the UPE of an MNE Group and as such are not consolidated in the MNE Group’s consolidated financial statements nor included in its CbC report. Therefore, CbC reports will not support a tax administration in identifying Joint Ventures that are in scope of the GMT. Other sources of data that may be used for this purpose are considered below in Section 1.3. The impact of duplicate CbC reports

11. When CbC reporting was first introduced for fiscal years beginning on or after 1 January 2016, a number of jurisdictions introduced provisions to allow Constituent Entities that were not the UPE of their MNE Group (“surrogate parent entities” or SPEs) to file a CbC report on a voluntary basis. These CbC reports were exchanged with tax administrations in other jurisdictions where the MNE Group had Constituent Entities. Where the UPE of an MNE Group was resident in a jurisdiction that had not introduced a CbC reporting filing requirement or had not entered into agreements for the exchange of CbC reports, this SPE filing helped the MNE Group to avoid being required to file a CbC report under “local filing” rules in potentially multiple jurisdictions.

12. As more jurisdictions have introduced filing requirements and exchange agreements, the need for SPE filing has reduced significantly, but some MNE Groups have continued to file CbC reports in two or more jurisdictions, each of which are exchanged with tax administrations in other jurisdictions. This means that there are cases where a tax administration receives multiple versions of an MNE Group’s CbC report from different filing jurisdictions. There have also been cases where an MNE Group has filed an updated CbC report for a fiscal year (e.g. correcting errors contained in its original CbC report) but this is not identified as an update to an existing report when it is filed and/or exchanged. Again, this could result in a tax administration receiving two versions of an MNE Group’s CbC report, this time containing different information. In each case the fact that more than one CbC report is being received on the same MNE Group which could inflate the results of a process to identify MNE Groups in scope of the GMT. This issue could be addressed if a tax administration matches CbC reports with local Constituent Entities and ensures that any duplicate CbC reports are disregarded for the purposes of an estimate. The de minimis threshold

13. Pillar 2 incorporates a de minimis threshold whereby an MNE Group’s Constituent Entities in a jurisdiction are not subject to the GMT where the MNE Group has both: • an average GloBE Revenue for the jurisdiction that is less than EUR 10 million, and • an average GloBE Income or loss for the jurisdiction that is either a loss or less than EUR 1 million, computed on a three-year average basis.

14. BEPS Action 13 does not include any de minimis threshold and specifically provides that Constituent Entities cannot be excluded from a CbC report on grounds of size or materiality. Therefore, all jurisdictions where an MNE Group has Constituent Entities will be included in its CbC report irrespective of the level of revenues or profits. That said, a CbC report does include information on an MNE Group’s Revenues and Profit (Loss) before Income Tax calculated on a jurisdictional basis. Therefore, while a CbC report is not sufficient to determine whether an MNE Group does qualify for the de minimis threshold in a particular jurisdiction for a period, it may contain enough information to indicate whether an MNE Group might qualify or if it is unlikely to do so. Taxpayer Identification Numbers

15. Under BEPS Action 13, a CbC report should include the Taxpayer Identification Number (TIN) for every Constituent Entity that has a TIN issued to it in its residence jurisdiction or, in the case of a PE the jurisdiction where it is located. This is important to allow a tax administration to reliably match a CbC report to the specific Constituent Entities that operate in its jurisdiction. However, in practice this is an area where tax administrations have raised serious concerns that MNE Groups are not including TINs for some or all Constituent Entities or are including incorrect TINs.

16. Missing or incorrect TINs should not prevent a tax administration from using CbC reports to identify the population of MNE Groups in scope of the GMT in its jurisdiction, but they can cause a challenge in using these reports to identify specific Constituent Entities that may be subject to the GMT. The extent of this challenge appears to vary from jurisdiction to jurisdiction, with some tax administrations able to match CbC reports to taxpayers in the jurisdiction more easily while others find this more difficult. Access to CbC reports

17. As mentioned above, the majority of IF members have access to CbC reports on foreign-headed MNE Groups, receiving these CbC reports under automatic exchange of information. However, a significant minority of IF members, including many low-income and middle-income jurisdictions, do not currently have access to this data.

18. Ensuring the availability of CbC reports for all IF members who consider access a priority was identified as a key issue at the IF Plenary meeting held in Cape Town in April 2025 and work is currently under way to support members in achieving access to CbC reports in accordance with the timeframe set by each member. Where a jurisdiction does not currently have access to CbC reports, alternative sources of data that could be used for the purposes of estimating the population of MNE Groups in scope of the GMT in a jurisdiction are considered in Section 1.2 and Section 1.3 of this Toolkit. 1.1.3. Making a broad estimate of the number of in-scope MNE Groups in a jurisdiction

19. Where a tax administration has decided to use CbC reports for the purposes of estimating the population of MNE Groups in scope of the GMT, there are several ways in which this can be done.

20. The most straight-forward approach is simply to take the population of MNE Groups that filed a CbC report for a recent fiscal year and assume that this will broadly correspond with population that will be in scope of the GMT. In choosing a recent fiscal year to consider, it is important that this should not be so recent that the filing and exchange of CbC reports for the year is not yet complete (including allowing some time for late filings and exchanges) but not be so long ago that material changes to the in-scope population would be expected. When relying on data from a recent fiscal year it needs to be borne in mind that MNE Groups headquartered in many jurisdictions may have fiscal years that begin on any calendar date and that these fiscal years typically have a length of 12 months. Furthermore, while the jurisdiction of the tax administration undertaking an estimate may have an earlier filing deadline, in many jurisdictions a CbC report is only required to be filed 12 months following the end of the fiscal year (the latest filing deadline permitted under Action 13) and CbC reports are exchanged 15 months following the end of the fiscal year (the latest exchange deadline permitted under the CbC reporting multilateral competent authority agreement). Based on these assumptions, if a tax administration in undertaking the exercise to estimate the in-scope population of MNE Groups in early-2026, then: • the filing of CbC reports for fiscal years commencing in 2025 will not yet have started, • the filing and exchange of CbC reports for fiscal years commencing in 2024 will have started but will not yet be complete, • the filing and exchange of CbC reports for fiscal years commencing in 2023 should be complete but there may still be a number of filings and/or exchanges outstanding, and • the filing and exchange of CbC reports for fiscal years commencing in 2022 and earlier years should now be complete.

21. In this example, a tax administration could choose to base its estimate on CbC reports for fiscal years commencing in 2023, but feedback from tax administrations suggests that using CbC reports for fiscal years commencing in 2022 may give a more complete picture. Ultimately, it is a decision to be taken by a tax administration whether to rely upon data from an earlier year which may be more complete, or data from a more recent year which may be more up to date.

22. An MNE Group is in scope of the GMT if it has consolidated group revenues above the threshold in two out of the last four fiscal years preceding the reporting fiscal year. As such, basing an estimate of an in-scope population on only a single year of CbC reporting data is unlikely to be entirely accurate. Despite this, if a tax administration only requires a broad estimate of the likely in-scope population for its current purposes (e.g. if the first fiscal year in which the GMT will apply in the jurisdiction is still in the future and so the in-scope population may in any case change before rules begin to apply) then this simple approach may be sufficient for the tax administration’s needs. 1.1.4. Making a more accurate estimate of the population of in-scope MNE Groups in a jurisdiction for a particular year

23. An important difference in the way in which the revenue thresholds under BEPS Action 13 and Pillar 2 differ is that an MNE Group is in scope of CbC reporting if it has consolidated group revenues that meet the threshold in the immediately previous fiscal year whereas an MNE Group is in scope of the GMT if it meets the threshold in two out of the four previous fiscal years. This smooths the effect of revenue volatility when determining if an MNE Group is in scope of the GMT. Despite this difference, if a tax administration needs a more accurate estimate of the population of MNE Groups in scope of the GMT for a particular year than that described in the previous section, it may still be possible to use CbC reports to achieve this.

24. For example, if a tax administration is undertaking an exercise in early 2026 to estimate the likely in-scope population for the GMT for fiscal years beginning in 2024, it could undertake the following steps. • The tax administration should identify the population of MNE Groups filing a CbC report for fiscal years beginning in 2021, 2022 and 2023. This should provide a good indicator of the MNE Groups that had consolidated group revenues above the threshold in their fiscal years beginning in 2020, 2021 and 2022 (because the CbC reporting threshold is based on consolidated group revenues in the immediately preceding fiscal year). • If an MNE Group filed a CbC report for two of these fiscal years (so 2021 and 2022, 2021 and 2023 or 2022 and 2023) then it is likely that the MNE Group will be in scope of the GMT for its fiscal year commencing in 2024. • If an MNE Group filed a CbC report for only one of these fiscal years (so either 2021, 2022 or 2023 only), the tax administration may use another source of data such as the MNE Group’s published consolidated financial statements to test whether the group had consolidated group revenues above the threshold in its fiscal year beginning in 2023). This is because an MNE Group’s consolidated financial statements for 2023 will generally be available (e.g. on the group’s website) before its CbC report for its fiscal year beginning in 2024 is filed and exchanged. If an MNE Group filed a CbC report for either 2021, 2022 or 2023 and according to its published consolidated financial statements it had consolidated group revenues above the threshold in 2023, then it is likely that the MNE Group will be in scope of the GMT for its fiscal year commencing in 2024. • For completeness, where an MNE Group filed a CbC report for either 2021 or 2022, but not for 2023, the tax administration may still consider consulting the MNE Group’s consolidated financial statements for its fiscal year commencing in 2022 to see whether it had consolidated group revenues above the threshold. This is because, while the deadline for filing and exchanging CbC reports for fiscal years commencing in 2023 has passed, there may have been a delay meaning that the CbC report has not yet been received by the tax administration, in particular if the fiscal year of the MNE Group has a start date late in the calendar year.

1.2. Commercial datasets

1. Tax administrations may rely on commercial data sources to estimate the population of MNE Groups in scope of the GMT. Such estimates can complement analyses based on CbC reporting data or serve as the basis for a standalone approach where CbC reporting data is not available. Commercial databases, including Orbis (Box 1), Compustat, Factset, and similar sources, typically provide information on ownership structures and financial accounts that can be used to approximate the in-scope population. Commercial databases also usually include other potentially relevant information. Data on the sector classifications of groups may also facilitate the exclusion of certain excluded groups, such as international organisations. In some cases, these datasets also include TINs, which facilitate matching Corporate Income Tax (CIT) returns or financial statements.

2. Commercial datasets have a number of limitations which need to be borne in mind when estimating in-scope populations. First, the precision of the assessment may be limited by missing or outdated financial information and ownership links in commercial datasets. Second, there may be differences in ownership concepts between the GloBE Rules and the commercial dataset used. Specifically, the GloBE Rules definition of UPE refers to control while the commercial datasets may refer purely to ownership. Third, while commercial datasets can include information on the legal form of companies, which may be used to identify PEs or excluded entities, coverage of such variables is often imperfect.

Box 1. Illustration of a possible commercial dataset

The Orbis dataset is an example of a commercial dataset used by the OECD and the World Bank

in bilateral engagements with countries concerning the GMT. It is a commercial dataset commercialised by Moody’s Analytics – Bureau Van Dijk, containing information on over 620 million companies worldwide, using approximately 170 different sources of data.

Orbis may be used to identify group structure and estimate revenue of companies covered. The Orbis dataset contains extensive information on ownership links between Global Ultimate Owners (GUO) and their subsidiaries as well as financial statement information, both at the consolidated and unconsolidated level. The information on entity ownership may be used to identify likely UPEs, using the GUO concept, and their subsidiaries.

Orbis coverage is imperfect, especially at the subsidiary level (unconsolidated accounts), but

also in terms of ownership links. Financial information is especially well covered at the consolidated level while unconsolidated data is less reliable. Coverage also depends on jurisdictions, with European subsidiaries being on average somewhat better covered than subsidiaries located in other regions. Nonetheless, a comparison of the number of in-scope MNE Groups with counts of groups filing CbC reports for a number of jurisdictions across multiple regions suggests that the coverage of ownership links is relatively good globally. Orbis may therefore be supplemented with information from other sources, such as administrative data, to increase reliability.

The UPE concept from the GloBE Rules can be proxied by the GUO in Orbis. However, these concepts may differ since the GUO concept only refers to a share of ownership rather than to control as in the UPE definition. Under the GloBE Rules, a UPE is defined as an entity which (i) owns directly or indirectly a Controlling Interest in any other entity; and (ii) is not owned, with a Controlling Interest, directly or indirectly by another entity.¹ Similarly, Constituent Entities can be approximated by subsidiaries. However, specific types of entities such as PEs or investment funds may not be easily identified using Orbis data. Information on entities’ legal form can be used for this purpose, e.g. a PE may typically be classified as a branch or a foreign company, but with large variation in coverage across jurisdictions.

Orbis data may be accessed in three ways: via the online Orbis platform, the historical Orbis disks (or related solutions), and through the Wharton Research Data Services (WRDS) from the Wharton School at the University of Pennsylvania (Kalemlİ-Özcan et al., 2024[1]). Each access mode involves different cost considerations, coverage and operational trade-offs. While the historical Orbis access provides the most complete access to data, it is more common that tax administrations will have online access via the website. Online access allows to consult and download current and historical financial data, as well as latest available ownership links. Because the online data is updated frequently, it provides the most up-to-date picture of groups’ structures. However, this approach to data access may limit the reproducibility of analyses. On the other hand, historical disks (“flat files”) provide information as observed at the end of each year of observation. The timeliness of the disks is, however, limited, and the data usually suffers a one- or two-year lag. Data obtained through the WRDS covers only European companies (this subset of Orbis data is often referred to as the Amadeus dataset) and has generally similar features as data downloaded via the online interface.

Table 1. Ownership data from Orbis is relatively complete

The table below provides an illustration of the data that may be available on Orbis for a sample of countries.

Note: Column 1 shows the total number of entities recorded in Orbis for each country. Column 2 indicates the total number of entities identified as headquarters (i.e. GUO) of a multinational group in each country. Column 3 indicates how many of these groups were found to be likely in scope of the GMT. Column 4 shows the number of subsidiaries of (domestic and foreign) multinational groups in each country. Columns 5 and 6 display the number of subsidiaries that are part of MNE Groups with revenue above EUR 500 million or EUR 750 million, respectively. Column 7 shows the number of subsidiaries that belong to an MNE Group likely to be in scope of the GMT. Column 8 shows the count of multinational groups likely to be in scope of the GMT in each country. Columns 9 and 10 indicate the number of subsidiaries and groups from CbC reports, for reference. Source: Bachas et al. (2025[2])A Controlling Interest is an Ownership Interest in an Entity such that the interest holder: (a) is required to consolidate the assets… of the Entity on a line-by-line basis in accordance with an Acceptable Financial Accounting Standard; or (b) would have been required to consolidate (...) if the interest holder had prepared Consolidated Financial Statements.

1. In principle, several approaches can be taken to estimating the in-scope population using commercial databases. One approach¹⁸ involves three distinct steps: i. Identifying MNE Groups likely to be in scope of the GMT at the global level, ii. Identifying subsidiaries of likely MNE Groups operating in a given jurisdiction, and iii. Merging these datasets to produce the final list of in-scope subsidiaries in this jurisdiction. The following subsections describe these steps in sequence.

Box 2. Ex f T d’ c c c

As part of its decision-making process, Thailand required that a local GMT impact assessment be released. To inform the legislative process, the Revenue Department of Thailand estimated the in-scope population and led an impact assessment.

The Revenue Department first received exchanged CbCR data in 2023, covering fiscal year 2021 and involving exchanges with only 40 jurisdictions. Therefore, the estimation of in-scope MNE groups was primarily based on Orbis. Financial information was also sourced from Orbis. Since not all Thai MNEs are required to prepare consolidated financial statements, and given unconsolidated financial data is not as well covered in developing countries Orbis, the tax administration noted that some in-scope entities may not captured by this process.

A second component of the analysis undertaken by the tax administration focused on tax incentives. After having estimated the potential additional revenue from the implementation of the GMT, the Revenue Department analysed the main tax incentives available in Thailand to better understand the drivers of the observed undertaxed profits. To this end, Orbis data were merged with CIT returns for entities reporting low effective tax rates. For Thailand, the availability of TINs in Orbis facilitated the match with tax return data. This approach allowed the Revenue Department to understand to which extent low effective tax rates were attributable to taxpayers benefitting from tax incentives such as tax holidays.

The impact assessment concluded that implementing the GMT would result in significant revenue gains for Thailand. Following this assessment and a consultation process, Thailand has enacted the GloBE Rules legislation as of January 2025.

External expertise was brought under the auspices of the Asian Development Bank to assist with aspects of the data analysis. The OECD also provided guidance and support for the impact assessment as part of the Pilot programmes on GMT implementation.

18 This is the approach taken by the OECD and the World Bank working in collaboration with several jurisdictions to estimate the in-scope population as part of an economic impact assessment of the GMT using the Orbis database.

1.2.1. Create list of entities in scope globally

1. An appropriate first step in the use of a commercial data set is to identify all entities with revenue above the GMT threshold. To this end, a subset of the commercial dataset should be constructed including all entities (UPEs and subsidiaries) that report revenue exceeding EUR 750 million in at least one of the years under review. As a practical approach, jurisdictions may first filter entities with consolidated financial statements and subsequently apply the group revenue threshold. This sequencing helps narrow the population and prioritise entities that are either UPEs or relatively high in the ownership chain. This ensures that if financial information is missing for an ultimate parent but one of its identified subsidiary exceeds the revenue threshold, then the entire group is also included in the in-scope population.

2. Further steps may be taken to refine the list once a dataset composed of all groups with revenue above EUR 750 million has been constituted. In particular, the GloBE scoping rule requiring that group revenue exceeds the threshold in at least two of the previous four fiscal years can be applied.¹⁹ At this stage, a number of common data cleaning procedures and checks may also be applied, such as removing duplicates, harmonising data formats, or identifying and addressing outliers. 1.2.2. Create list of subsidiaries operating in a jurisdiction

3. As an initial step, all entities operating in the jurisdiction under review can be identified. Practically, this could be done using the location variable in the dataset to select the relevant jurisdiction. To limit the scope of the query, the search should then be restricted to entities that are subsidiaries of MNE Groups. At this stage, subsidiaries of both in-scope and out-of-scope MNE Groups should be retained. The resulting dataset should include ownership information, notably the name and identification number of each subsidiary and its UPE. The dataset may also contain PEs, but the coverage of such entities is typically limited, even in jurisdictions that are otherwise well represented in commercial databases, and additional data may therefore be required. 1.2.3. Create list of in-scope subsidiaries in a jurisdiction

4. To derive the list of in-scope subsidiaries operating in a given jurisdiction, the datasets produced in the two previous subsections should be merged. This step can be performed using statistical software. In practice, this involves combining the list of in-scope MNE Groups at the global level with the list of entities operating in the jurisdiction and retaining only matched records based on ownership information. For example, if using Orbis data, this match can be conducted using the identification number (BvD ID) of the GUO.

5. The resulting dataset should include domestic subsidiaries of MNEs that meet the revenue threshold. This list may be linked with other data sources available to the tax administration, such as CIT returns, financial statements, or CbCR data. Where available, TINs contained in commercial datasets can facilitate matching with administrative records. In their absence, matching may be performed using company names, subject to appropriate validation checks.

6. The de minimis exclusion may also be incorporated into the analysis. Under this rule, an MNE Group’s subsidiaries in a jurisdiction are excluded from the top-up tax calculation where the group has limited operations in that jurisdiction, defined as jurisdictions where the MNE has (i) an average GloBE revenue that is less than €10m, and (ii) an average GloBE Income or loss that is either a loss or less than €1m, computed on a three-year average basis. These exclusions apply on a jurisdictional basis, i.e. to the MNE Groupsʹ total GloBE revenue and GloBE Income in the jurisdiction. If both conditions are satisfied, the subsidiary should be excluded from the dataset. However, as this information would require 19 This can be done using a statistical software. unconsolidated information, which is generally less well covered, this step would likely involve merging the subsidiary list with either financial statements or tax returns if these are available.

1.3. Other sources of data to estimate in-scope population

1. If a tax administration does not have access to CbC reports nor to reliable commercial data, the following alternative sources of data may also be used to estimate the population of MNE Groups in scope of the GMT. • Aggregated CbC reporting data published by the OECD. • Data or intelligence held by the tax administration. • Consolidated financial statements. • Pre-filing registration data.

2. These sources of data may also be used to supplement the results of an analysis using CbC reports or commercial data. However, when using multiple sources, it is important to be aware of the risk of duplicative results, overestimating the in-scope population. As such, it will be important to take steps to identify and address this duplication or, as a minimum, recognise its potential impact. Jurisdictions facing these challenges may wish to reach out to the OECD or to other partner organisations providing technical assistance on minimum tax (see Box 4). 1.3.1. Aggregated CbC reporting data published by the OECD

3. Under BEPS Action 11, each year the OECD collects from IF members anonymised and aggregated data extracted from CbC reports filed by MNE Groups in each jurisdiction. This data is released as part of the annual Corporate Tax Statistics publication, allowing stakeholders that do not have access to CbC reports to undertake analyses. The latest version of this data, released in July 2025 includes data based on CbC reports filed for fiscal years commencing in 2021 and is available to all tax administrations including those that have not implemented Action 13.

4. In order to conduct a search of the aggregated CbC reporting data, a tax administration should: • open the OECD Data Explorer at this link, • select the table of data entitled Country-by-country reporting (CbCR) - Aggregate totals by jurisdiction – Corporate Tax Statistics, • under the heading Refine your data selection, it should: • click on Time Period to select the latest year of data available, • click on Reference Area and select Deselect All, • click on Counterpart Area and select the name of its own jurisdiction (ensuring no other jurisdictions are selected), and • click on Apply.²⁰ 20 FAQs regarding the OECD data explorer, as well as an instructional video, can be found at this link.

Figure 1. Applying filters to aggregated CbC reporting data in the OECD Data Explorer

1. Once this search is completed, a table will be presented including aggregated data provided by IF members on CbC reports filed by UPEs resident in their jurisdiction that contain one or more Constituent Entities in the jurisdiction of the tax administration undertaking the search. The first two columns of this table will include the Reference Area (i.e. the name of the jurisdiction in which the CbC report was filed) and the number of MNE Groups that filed a CbC report which included Constituent Entities in the jurisdiction of the tax administration. While many IF members that provide aggregated CbC reporting data include information on the location of Constituent Entities, this is not always the case. Some members provide data aggregated by continent rather than by jurisdiction or only provide this data for a limited number of jurisdictions. Information on the level of detail provided by each IF member can be found in table 7.2 of Corporate Tax Statistics 2025.²¹ The tax administration undertaking the search can aggregate the numbers in this column to determine a broad estimate of the total number of MNE Groups headquartered in jurisdictions that provided this level of data that may be in scope of the GMT in its jurisdiction (noting that this is based on historic data that is several years old). This analysis also allows the tax administration to see how many of these MNE Groups are likely to have UPEs resident in each IF member where CbC reporting is required and that contributed to the data. 21 OECD (2025), Corporate Tax Statistics 2025, OECD Publishing, Paris, https://doi.org/10.1787/6a915941-en.

Figure 2. Estimating the number of in-scope MNE groups by UPE jurisdiction using aggregated CbC reporting data

1. This indicator of the possible number of in-scope MNEs across a number of UPE jurisdictions may be sufficient for the purposes of the tax administration undertaking the exercise. However, if the tax administration wishes to undertake further work to better understand which MNE Groups are likely to be in scope of the GMT, it may compare the results of this analysis with other information it holds within the tax administration. For example, if based on the aggregated CbC reporting data it knows that there were 10 MNE Groups with the UPE located in Jurisdiction X that filed CbC reports including local Constituent Entities, it may be able to use its own intelligence to determine which are the 10 largest MNE Groups from Jurisdiction X with operations in its jurisdiction. 1.3.2. Data or intelligence held by the tax administration

2. Tax administrations will often hold large amounts of data on their corporate taxpayers, provided within or alongside a taxpayer’s CIT return or gathered in the process of a tax audit, an advance pricing arrangement or other compliance action. For example, in some jurisdictions a taxpayer will be required to tick a box on their tax return if they are a member of a large MNE Group (as defined under local tax law). The existence and reliability of this data will vary from jurisdiction to jurisdiction depending upon local requirements and enforcement but could be an important and useful tool for a tax administration that does not have access to some of the other sources described in this Module. 1.3.3. Consolidated financial statements

3. Most large MNE Groups prepare annual consolidated financial statements that can be obtained separately or as part of an annual report on the group’s business and operations. Where an MNE Group is listed on a securities exchange the publication of such financial statements will typically be required, but large privately held MNE Groups also often make consolidated financial statements available publicly for the benefit of the press, analysts, lenders and investors. These financial statements (or relevant extracts from the financial statements) are often available via the securities exchange website, a jurisdiction’s companies registry or chamber of commerce or, often more practically, the MNE Group’s website and can be available within three months of the fiscal year end (or sooner), which is significantly earlier than CbC reports.

4. In undertaking an estimate of the population of in-scope MNE Groups, a tax administration may seek views from its audit managers and other officials as to which taxpayers are likely to be members of MNE Groups that could be within the scope of the GMT and then use the publicly available consolidated financial statements of these MNE Groups to confirm whether this is the case. As described above for the purposes of using CbC reports, this can either be done using a simplified approach by looking at the consolidated financial statements for the most recent fiscal year for which information is available, or using a more detailed multi-year approach to test whether the MNE Group had consolidated group revenues above the threshold in two out of the four fiscal years immediately preceding a specific period. In addition, under International Accounting Standard 12 (IAS 12), MNE Groups that prepare consolidated financial statements using IFRS are required to disclose that they are in scope of the GMT for a period, as well as their current tax expense related to the GMT and other Pillar 2-specific disclosures.

Box 3. Ex f U d K gd ’ u f d -scope population

The United Kingdom is an example of a jurisdiction that has used a number of different sources of data to estimate the number of MNE groups that will potentially be in-scope of the GMT.

• CbC reporting data was used to identify MNE groups that had consolidated group revenues above the EUR 750 million threshold for a number of fiscal years preceding the introduction of the GMT and so may be in-scope of the GMT for fiscal years commencing in 2024. Customer Compliance Managers (CCMs) in HM Revenue and Customs’ (HMRC) Large Business unit were also engaged in this exercise to ensure that any changes in an MNE group’s profile or position that could impact whether it was likely to be subject to the GMT in practice were taken into account. • HMRC also relied on information held by the tax administration and the experience of officials working with potentially in-scope MNEs, including CCMs, to identify wholly domestic groups (i.e. those with all Constituent Entities resident in the United Kingdom and with no foreign PEs) that could be within scope of the GMT. This was then confirmed using consolidated group revenue figures taken from published consolidated financial statements. • Potential Joint Ventures that could be subject to the GMT in the United Kingdom were identified using commercial databases to search for entities that are precisely 50% owned by an MNE group or domestic group that is itself likely to be in-scope of the GMT.

1.3.4. Data obtained from registration requirements

1. For the purposes of preparing for the first GIR filings and for GMT revenue estimation, it is generally not necessary that a tax administration identifies every in-scope MNE Group and local constituent entity in advance of the first GIR filing/notification deadline, but an understanding of the likely scale of the in-scope population and the broad profile of in-scope MNE Groups is beneficial. It is expected that, for the majority of tax administrations, the data sources mentioned previously in this section will be sufficient for these purposes. These sources also have the additional benefit that they are pre-existing and so their use does not imply any additional burden on MNE Groups or on tax administrations (beyond any requisite conditions to access the data).

2. Where a tax administration does not have access to CbC reports or reliable commercial databases, and the other alternate sources of data mentioned in this section are not sufficient, then there is the possibility for a jurisdiction to introduce a requirement for local Constituent Entities that are part of in-scope MNE Groups to register with its tax administration after the end of the first fiscal year for which they will be in scope, but in advance of the GIR filing/notification deadline. This will provide the tax administration with useful information on the MNE Groups and Constituent Entities that will be in scope of the GMT, but this approach does imply an additional burden on the tax administration to implement and operate a registration process and on MNE Groups to comply with such a process. As any registration requirement relies on action to be taken by an MNE Group, the accuracy and completeness of the data it provides also depends upon awareness of the requirement and compliance with that requirement by MNE Groups. More information on registration requirements is included in Module 4.

1.4. Estimating top-up tax revenue

1. This section explains, at a high level, how jurisdictions can estimate entity-level top-up tax liabilities under the GMT using available data sources.²² The GloBE computation is based on three main elements: GloBE income, covered taxes and the Substance-Based Income Exclusion (SBIE). Figure 4 illustrates how these concepts interact in the top-up tax calculation. Together, these variables determine the amount of top-up tax due in a jurisdiction. The jurisdictional Effective Tax Rate (ETR) is then calculated as the ratio of covered taxes to GloBE income, and the applicable top-up tax percentage corresponds to the difference between this ETR and the 15% minimum tax rate under the GMT. This top-up percentage is then applied to jurisdictional excess profit, defined as GloBE income after deduction of the SBIE. A detailed methodology for estimating revenues from QDMTTs, including assessing the impact the treatment of different kinds of tax incentives is presented in a forthcoming OECD-World Bank publication (OECD-World Bank, Forthcoming 2026[3])).

Figure 3. Calculation of top-up taxes under GloBE

22 This section does not cover policy considerations that may influence whether jurisdictions should or should not introduce a given component of the GMT rules. These considerations are discussed further in the Minimum Tax Implementation Handbook (Pillar Two).

Box 4. Assistance from International Organisations on GMT revenue estimation

The OECD has provided assistance to jurisdictions seeking to undertake local GMT revenue estimations. Revenue estimation results based on anonymised and aggregated CbC reporting data has also been made available to all IF member jurisdictions.

Bilateral assistance can take several forms, including:

1. Providing technical advice to tax administrations, for example on the interaction between the GMT and existing tax incentives. 2. Sharing scripts for statistical software in different programming languages to support calculations of jurisdictional effective tax rates and top up tax liabilities. 3. Supporting tax administrations in the analysis of anonymised micro-data from tax returns or financial statements shared by jurisdictions on a confidential basis. When data availability permits, this may include analysis of the use of tax incentive use. Other International Organisation have also supported jurisdictions in assessing the impacts of the GMT. For example, the World Bank has engaged with several jurisdictions wishing to estimate the potential revenue impacts of the GMT (Bachas et al., 2025[2]), as have the IMF. The International Institute for Sustainable Development (IISD) has also worked with a number of jurisdictions to assess how tax incentives may be affected by the GMT.

1.4.1. Data approaches and limitations

1. The most precise approach to estimating potential revenue gains from introducing a QDMTT relies on entity-level data on ownership, income, taxes, tangible assets and payroll. After identifying the population of in-scope entities in a jurisdiction following steps described in previous sections, certain adjustments may be made to the data to better align the estimation with the GloBE Rules, and it is recommended that at least three years of data be gathered for more accurate results. While more years of data is usually preferable, the application of the de minimis exclusion is based on a three-year average.

2. Table 2 below presents different data availability scenarios, in a simplified form. The data required for the analysis may typically be found in a combination of financial statements, tax returns and CbC reporting data (Scenario 1). However, the availability and completeness of these datasets may vary across jurisdictions, and different scenarios are presented in the table ranging from extensive data availability (Scenario 1) to limited data availability (Scenario 5).²³

Table 2. Key data scenarios and recommended data sources

23 In the absence of any tax return, financial statement or CbC reporting data, jurisdictions may consider jurisdictionspecific QDMTT estimates based on publicly available and aggregated data, which are available on request from the OECD. These estimates have been shared with officials of Inclusive Framework members on a bilateral basis. It is important to note that these include important caveats as they rely on aggregated data.

(1) Adjustment for Qualified Refundable Tax Credits (QRTCs) or non-refundable tax credits also involves variables from tax return. (2) Includes the scenario where financial statement items are reported in the tax return. (3) Imputation using CbCR information on number of employees multiplied by average wages from other sources (e.g. survey). (4) Financial statements referred to here may be obtainable from a commercial registry in which firms may be obliged to report. A commercial database (such as Compustat or Orbis) might be another source of financial statement data, although the coverage of such databases varies considerably between jurisdictions. (5) Imputation using other data sources on payroll and tangible assets (e.g. business statistics). Source: Based on forthcoming OECD-World Bank paper (Forthcoming 2026[3])

1. CbC reporting data provides the best starting point for identifying in-scope entities (see Section 1.1) and contains useful information for the construction of GloBE variables. Since CbC reports contain information on the global allocation of income, profit, taxes paid and economic substance, they may be used to approximate GloBE income, Covered Taxes, tangible assets and payroll (see Section 1.1.2 for a discussion on the appropriate use of CbCR data). However, this data may not be available to all jurisdictions as discussed above.

2. Financial accounts at the entity level provide the preferred starting point for the estimation of undertaxed profits, especially when they can be linked with tax return data. The GloBE Rules define the calculation of each Constituent Entity’s ETR based on the income and tax amounts from financial statements. The starting point for GloBE Income is, for example, the financial accounting net income or loss (FANIL), with some appropriate adjustments. Where financial accounts can be linked with tax return data, additional adjustments may be made to Covered Taxes, such as use of qualifying tax incentives, qualifying refundable tax credits and of deferred tax assets, such as loss carry-forwards.

3. Where financial accounts data is not readily available to the tax administration, the revenue estimation may rely upon other data sources. If financial accounting data is not collected for tax purposes, jurisdictions should assess whether it can be obtained from other government bodies and matched with administrative tax data. Tax administrations may also consider commercial providers like Orbis, noting that data quality and ownership coverage vary by country. Where neither source is feasible, GloBE concepts may be approximated using administrative tax data, subject to important limitations.

4. Imputation of information should be used only as a last resort when data for a variable or observation is missing. It involves replacing missing or inconsistent values with reasonable substitutes to preserve dataset usability. Common approaches include using overall averages or medians, or, where values differ across groups (e.g. sectors), subgroup averages or medians. Where sufficient data is available, more advanced methods such as regression-based imputation may also be applied. 1.4.2. Main adjustments for the estimation of top-up tax revenue

5. This section provides an overview of the main concepts and adjustments required for the estimation of QDMTT revenue in a given jurisdiction. More details can be found in a forthcoming OECD-World Bank guide to QDMTT estimation (OECD-World Bank, Forthcoming 2026[3]). Potential revenue from the IIR and the UTPR are not discussed here, though many of the data sources here may also be relevant for estimation of IIR revenue estimation. Jurisdictional blending

6. Under the jurisdictional blending rule, the GloBE Income, Covered Taxes and SBIE of all subsidiaries of the same MNE Group within a jurisdiction must be aggregated when performing estimates. This requires group structure information to identify and combine the relevant entities. Where such information is unavailable, calculations may be undertaken at the individual entity level as an approximation, but this approach is likely to overestimate revenue. This is because under the blending rules that are part of the GMT calculation, low-taxed profit in one entity can be offset by higher-taxed profit in another entity. If this is not taken into account by undertaking calculations at the jurisdiction level, revenues may be overstated. GloBE Income

7. Under the rules, GloBE Income is derived from FANIL, as reported in consolidated financial statements, subject to a series of adjustments intended to better align the measure with taxable income.²⁴ Some of the main adjustments are explained below.

8. A key adjustment is the addition of Covered Taxes. Covered Taxes broadly correspond to the net tax expense and profit before tax is equal to FANIL plus net tax expense, so that profit before tax provides a practical starting point for estimating GloBE Income using firm-level data. Jurisdictions are therefore encouraged to rely on profit before tax, or a closely related accounting income measure, where available. Preferred sources include profit before tax reported in financial statements or in tax returns before jurisdiction-specific tax adjustments, while measures reported after such adjustments are less suitable because they reflect domestic tax rules that may not align with GloBE adjustments. Taxable income is generally a less suitable proxy, as it already incorporates exemptions and deductions that are likely to differ from the GloBE Rules. Where profit before tax is not directly reported, it may be approximated using reported revenue and cost items before tax adjustments.

9. A second key adjustment is the subtraction of dividend income. Since dividend income is typically reported separately in tax returns, it is recommended that jurisdictions make this adjustment. While an exception to the exclusion of dividend income is made for short term portfolio shareholding, it is usually not possible to determine this specific amount, it is recommended that all dividend income be deducted.

10. Lastly, certain types of tax credits should be added to GloBE Income. Under the GloBE Rules, refundable credits, and marketable or transferable credits, which “qualify” are included in GloBE Income. Other tax credits are excluded and only reduce covered taxes. Covered Taxes

11. Under the GloBE Rules, Covered Taxes are based on the current tax expense reported in a company’s financial statements. Covered taxes are limited to taxes on corporate income, including relevant foreign taxes such as withholding and CFC taxes, and excluding non-income taxes. While the rules rely 24 The GloBE Information Return (GIR) lists all necessary adjustments to FANIL following the GloBE Rules, including net taxes, dividends, equity gains and losses, etc. on financial accounting data, jurisdictions can generally approximate Covered Taxes using the amount of CIT accrued for the year in tax returns. In practice, tax return data often provides a workable starting point and may be better suited for applying key adjustments where detailed financial statement breakdowns are not available.

12. When using tax return data, jurisdictions should consider applying a limited set of priority adjustments to improve alignment with the GloBE framework. In particular, it is important to account for loss carryforwards, which affects Covered Taxes through deferred tax. Where possible, estimates should adjust for losses carried forward and used, based on information commonly reported in tax returns. By contrast, other deferred tax timing differences are often difficult to measure with available data and may be assumed to average out over several years. Using multi-year averages or GloBE Income and Covered Taxes can help smooth these effects.

13. Jurisdictions should also adjust, where feasible, for certain permanent differences. In particular, withholding taxes and similar income taxes should be appropriately included or excluded depending on whether they relate to covered income. Adjustments might also be required with respect to qualifying refundable or transferable tax credits. As part of the adoption of the Side-by-Side package by the Inclusive Framework on 5 January 2026, a Substance-Based Tax Incentive Safe Harbour was agreed. It allows an MNE group to treat certain substance-based tax incentives as an addition to the covered taxes of the Constituent Entities located in the jurisdiction. These adjustments are limited by substance cap that is calculated by reference to the MNE Group’s payroll and tangible assets in the jurisdiction. When estimating the impact of tax credits or other expenditure-based incentives on Covered Taxes consideration should be given to whether in-scope MNE Groups are likely to be recipients of such qualified tax incentives eligible for the Safe Harbour.²⁵ Substance-Based Income Exclusion

14. The SBIE is the final element required to estimate entity-level top-up tax under the GloBE framework. It excludes a portion of income attributable to substantive economic activity in a jurisdiction, thereby reducing the amount of profit subject to top-up tax. The SBIE is determined as a percentage of the MNE Group’s payroll and tangible assets located in the jurisdiction. These percentages are higher, 10% of payroll and 8% of tangible assets, during an initial transition period and decline over time to reach final levels of 5% of payroll and tangible assets.

15. Data needed to estimate the SBIE are payroll expenses and the value of tangible assets and are typically reported in financial statements. CIT returns also often include a number of items from financial statements and may include data on payroll and tangible assets. Relevant tangible assets generally correspond to property, plant and equipment, and right-of-use assets. Where financial statement data are not available, these variables may be approximated using alternative sources, including tax return information and CbC reports, which provide data on tangible assets and employee headcount that can support payroll estimates where necessary. 1.4.3. Estimating QDMTT revenue

16. Once GloBE Income, Covered Taxes and the SBIE have been estimated, top-up tax can be calculated for each in-scope MNE Group and aggregated to derive total estimated QDMTT revenue for the jurisdiction. Practically, total QDMTT revenue corresponds to the sum of firm-level top-up tax amounts 25 For more information on Substance-based Tax Incentive Safe Harbour and Tax Incentives see OECD (2026), Tax Challenges Arising from the Digitalisation of the Economy – Global Anti-Base Erosion Model Rules (Pillar Two), Sideby-Side Package: Inclusive Framework on BEPS, OECD, https://www.oecd.org/content/dam/oecd/en/topics/policysub-issues/global-minimum-tax/side-by-side-package.pdf. across all in-scope groups. Jurisdictions may also wish to produce separate estimates reflecting transitional provisions that apply during the initial years of GMT implementation. Given data and modelling limitations, a range of robustness checks is recommended to assess the sensitivity of results to key assumptions and data choices.²⁶ Jurisdictions considering implementation should also consider resources such as the Handbook on GMT implementation, as well as by the World Bank. ²⁷

17. For the transition period, jurisdictions with access to CbC reports may consider complementary estimates that incorporate the CbC reporting transitional Safe Harbour. This Safe Harbour applies for 2024- 2027 and allows top-up tax to be treated as zero where simplified ETR, de minimis, or routine profit conditions are met,²⁸²⁹ based on CbC reporting indicators. Using CbC reporting data for this purpose can provide a simplified and practical basis for early-year estimates.

18. A number of steps can be taken to check the robustness of the QDMTT estimates. Some temporary adjustments to GloBE income or Covered Taxes may be omitted due to data limitations and the assumptions required for the estimation of top-up tax revenue. Robustness checks may include averaging the estimates of top-up taxes for each group over multiple years and examining the detailed financial statements of top contributors to the total QDMTT estimates.

19. After estimating the QDMTT revenue, jurisdictions may wish to explore the extent to which it is influenced by specific CIT tax incentives. Tax incentives are deviations from the standards tax system for specific taxpayers, projects or investments, designed to attain various social and economic objectives, like promoting FDI or innovation. For jurisdictions where the statutory tax rate exceeds 15%, any low-taxed profits and QDMTT revenue that exist in that jurisdiction are likely to result from tax incentives. The GMT affects some incentives more strongly than others (OECD, 2022[4]), and further changes to the treatment of tax incentives under the GMT were contained in the recently agreed SbS Package). Understanding how such incentives interact with the GMT therefore be a key component of the impact assessment and policy messages. Additional support for developing countries on how tax incentives can be adapted is provided by the OECD Global Relations Programme as well as by PCT members and regional tax organisations. 26 Jurisdictions may also wish to consult OECD-World Bank (forthcoming) Estimating QDMTT revenue using firm-level data: A Practical Guide. 27 See for example, World Bank. 2022. “The Global Minimum Tax: from agreement to implementation.” Overview booklet. Information and Communications for Development. World Bank, Washington, DC. 28 The simplified ETR test consists in assessing whether the ratio of adjusted covered taxes (income tax expense from the financial statements) over profit before tax from the CbC reporting profit and loss before income tax variable is above 15%. The de minimis test evaluates whether the jurisdiction has CbC reporting revenue of less than €10m and a CbC reporting profit and loss before income tax of less than €1m (including a loss). The routine profit test estimates if CbC reporting profit and loss before income tax is smaller or equal to the Substance Based Income Exclusion calculated according to the GloBE Rules. 29 The Transitional CbCR Safe Harbour was extended to 2027 as part of the Side-by-Side Package.

Module 2. Legal Implementation

Introduction

1. This module reviews the different legal mechanisms used by implementing jurisdictions to incorporate the GMT into their legal system and discusses how these choices can affect compliance and enforcement. Recognising that the role of tax administrations with respect to the legislative process varies significantly across jurisdictions, the module focuses on the implications of this process for subsequent compliance activities, as those considerations are relevant for all tax administrations^30.

2. The GloBE Rules (including the Commentary and agreed Administrative Guidance) are designed to operate as a common approach. Part of this common approach is that jurisdictions which choose to implement the rules do so in a way that is consistent with the outcomes provided for under the GloBE Rules. This consistency requirement, which is tested as part of the peer review process, does not require every jurisdiction to have the same rules. Rather it requires that the rules of different jurisdiction provide for the same outcomes. Whether the GloBE rules in different jurisdictions meet this consistency requirement will be a result not simply of how the rules are legislated but also how they are interpreted and applied. Consistency also has direct implications for compliance and enforcement, as greater consistency will result in a more predictable and efficient administration, reducing costs for both tax administrations and taxpayers. Where the rules in two different jurisdictions provide for the same outcome taxpayers will be able to streamline their compliance processes across different jurisdictions in which their group is operating. This translates into greater levels of voluntary and timely compliance, together with fewer demands for early certainty mechanisms (e.g. rulings, request for opinions or clarifications) and reduced risk of errors and disputes. Instead, the resources of tax administrations can be allocated to areas where they are most needed, such as detecting non-compliant taxpayers or high-risk cases. Lastly, cooperation and synergies between tax administrations from different jurisdictions that have also adopted the GloBE rules and are confronted with similar issues (e.g. interpretation issues, risk assessment, abusive arrangements) also is facilitated by consistency, thereby further improving efficiency in the application of the GMT.

3. The degree of consistency achieved in practice in the domestic legal framework is thus a critical consideration also for tax administrations when developing their GMT implementation plan. It determines the level and nature of the work needed to clarify domestic interpretations and ensure alignment with the GloBE Rules (e.g. in developing guidance, in engaging with taxpayers). It also determines the extent of the administrative adaptations required to support subsequent compliance activities and achieve an appropriate level of predictability and certainty, as further discussed in Module 3.

4. To assist the jurisdictions and tax administrations with this task, the following sections review the main legal mechanisms utilised to date by implementing jurisdictions to incorporate the GMT into their legal system, highlighting their possible implications for subsequent compliance strategies. To facilitate the analysis, these legal mechanisms have been grouped in three categories: approaches that directly affect the domestic legal framework through primary or secondary legislation (i.e. legislative techniques, section 2.1.), ways of ensuring that the domestic GMT rules include the latest agreed Administrative Guidance (i.e. legislative techniques for updating the legislation, section 2.2.) and approaches that indirectly affect the domestic legal framework by clarifying how those domestic rules are applied and administered in practice 30 This module is not intended to be used in any way to add to, alter or otherwise prejudice the peer review process or the associated assessment criteria to be discussed in Working Party 11. (i.e. interpretation mechanisms, section 2.3.). The key observations of the analysis of different approaches are summarised in the box below.

Key Observations on legal implementation of the GMT

Based on the discussions held in the context of the Amsterdam Dialogue, This Toolkit includes the following key observations on legal implementation GMT: • There are three different legislative techniques for incorporation of the Global Minimum Tax to incorporate the rules into domestic law. Jurisdictions will not always have a choice about which technique to adopt, due to constitutional or other constraints. Many implementing jurisdictions have adopted one legislative technique (either by choice or necessity), while some have adopted a combination of the different legislative techniques. There is considerable variation in approaches, though all the legislative techniques aim to ensure that the outcomes envisaged under the Model Rules are the same. • Incorporation of the GMT by cross-reference means that the domestic legislation refers to alreadyexisting provisions in the Model Rules, Commentary or Administrative Guidance approved by the IF (collectively the GloBE Rules) rather than restating them. This results in a single set of rules that facilitates compliance and lowers the risk of errors or disputes. This may translate into reduced demand on a jurisdiction’s legislative resources, requests for early certainty mechanisms (e.g. rulings or requests for clarification), as well as potentially fewer audits and disputes. Incorporation by cross-reference can be static (referring to provisions as written at a fixed time) or ambulatory (referring to provisions as they are changed in the future). • Incorporation of the GMT by repetition means repeating the GloBE Rules, or part of them (e.g. the Model Rules only) in domestic legislation. Jurisdictions who do not legislate in English or with constitutional constrains, may feel more comfortable incorporating the GloBE Rules or core aspects of them (such as the 10 Chapters of the Model Rules) in their own law by repetition. Repetition allows for a high degree of consistency with the GloBE Rules. • Incorporation of the GMT by rewrite means rewriting the GloBE Rules or part of them, organising and expressing them in ways more familiar to domestic users. This approach may be adopted due to legal constraints, or because the GloBE Rules drafting approach is different from the jurisdiction’s legal drafting conventions. It may have resource implications, in terms of ensuring the rewrite is accurate, and that adequate guidance is provided to taxpayers. This approach is often combined with other legislative techniques aimed at mitigating inconsistencies and reducing compliance burden, such as use of more easily amended secondary legislation and interpretation clauses (including some that work in a similar way to ambulatory incorporation by cross-reference). • Many jurisdictions have taken measures to make it easier to update their domestic GMT legislation to: o keep up with developments in the GloBE Rules, such as new administrative guidance or Safe Harbours, or o correct errors in domestic law. Techniques include use of secondary legislation, interpretation clauses, ambulatory references and allowing taxpayers to rely on GloBE developments which are not yet legally effective in the country. • Provision by the tax authority of public and private guidance on the rules is common and takes many forms. Public guidance has a wider impact, and is particularly common when the rules are introduced, to encourage compliance. Private guidance can also increase certainty, improve compliance and reduce disputes.

2.1. Legislative techniques

1. The Model Rules are a legislative template, intending to produce consistent outcomes but allowing jurisdictions flexibility in determining the form and legal mechanisms through which they are incorporated into domestic law.³¹ Implementing jurisdictions have used different legislative techniques to give effect to the GMT rules, each of which carries distinct implications for how consistency is achieved and maintained in practice. Based on the experience reported to date, there are three broad categories of legislative techniques jurisdictions can adopt. First, incorporation by reference, where domestic law simply states that all or some of the GloBE Rules as published by the IF are now part of domestic law. Second incorporation in the domestic legislation by repetition. Third, incorporation through a rewrite of the rules. Many jurisdictions adopt a mixture of these approaches. For example, they may rewrite the Model Rules, but incorporate the Commentary by repetition or reference. Jurisdictions will not always have a choice about which technique to adopt, due to constitutional or other constraints. 2.1.1. Incorporation by cross-reference

2. Some jurisdictions have incorporated most of the GloBE Rules into their domestic law through a cross-reference provision rather than by enacting them as independent provisions in their own law. Under this approach, the domestic law itself does not need to contain the majority of the GloBE Rules, beyond the imposition of the GMT liability on in-scope taxpayers. Most of the GloBE Rules become law by a direct reference to the GloBE Model Rules Commentary and Administrative Guidance, thereby making them a part of the jurisdiction’s legal system (“incorporation by cross-reference”).

3. There are two versions of this approach. Under an “ambulatory” incorporation by cross-reference approach, the domestic cross-reference automatically incorporates new guidance and updates agreed by the IF after the cross-reference was enacted (see discussion of New Zealand’s approach to incorporation set out in Box 5 below). Under the ambulatory approach, subsequent changes to the GloBE rules will usually only take effect only after a defined period (e.g. for fiscal years starting after the new guidance is published), and can be suspended or modified (for example, through a regulation or administrative instrument).

Box 5 N w Z d’ c c g G BE Ru (A bu y c by Cross-reference))

New Zealand has implemented the IIR (including on domestic income) and the UTPR but not a DMTT. The substantive GMT legislation in New Zealand is in four short sections and a one-page schedule (there are some additional administrative provisions, including the obligation to file a local return). The New Zealand approach is to incorporate the GloBE rules on an ambulatory basis. This is achieved through Section HP 3 of the Income Tax Act 2007, which states that the GloBE Rules, as modified by Schedule 25B, apply for a fiscal year. Schedule 25B incorporates the text of the Model Rules into New Zealand law, replacing the words “name of implementing jurisdiction” wherever they occur in the Model Rules with the words “New Zealand”. The definition of the GloBE rules in the NZ legislation refers to the Model Rules as approved by the IF on 14 December 2021 and as amended from time to time.

31 See in particular paragraphs 4 and 15 of OECD (2023), Minimum Tax Implementation Handbook (Pillar Two), OECD/G20 Base Erosion and Profit Shifting Project, OECD, Paris, https://www.oecd.org/tax/beps/minimum-taximplementation-handbook-pillar-two.pdf.

Section HP 3 says that the rules apply to a fiscal year “in accordance with” the commentary and administrative guidance published before the start of that year. Subsection (4) says that if commentary or guidance conflicts with the Model Rules, the commentary or guidance prevails. This confirms the cross-reference is ambulatory. All changes to the GloBE Rules are incorporated automatically without the need for any domestic law change, even if they over-ride prior law.

This minimalist approach is easier because New Zealand has not adopted a DMTT, which requires liability to be specified and can be accompanied by other locally specific rules.

As with any other law, the legislature retains the power to repeal the GMT, or amend any aspect of it, in respect of its operation in New Zealand. The legislation also gives the Government the specific power to suspend or vary new commentary or guidance by secondary legislation.

This approach is intended to minimise the cost of implementing and administering the law, commensurate with the relatively low level of revenue expected to be raised by the GMT in New Zealand.

1. Under a “static” incorporation by cross-reference approach, the cross-reference is limited to the version of the GloBE Rules agreed at a specific date, and subsequent guidance can only take effect once it is approved domestically – typically through an administrative instrument such as a ministerial notice or treasury order (see discussion of South Africa’s approach to incorporation set out in Box 6 below).

Box 6. S u Af c ’ c c g G BE Ru (S c c by C -

reference)

South Africa implemented the IIR and DMTT by reference to the GloBE Model Rules in the Global Minimum Tax Act (“GMTA”) and the Global Minimum Tax Administration Act (“GMTAA”) Section 2 of the GMTA provides that for purposes of the GMTA, the GloBE Model Rules apply for a Fiscal Year on the basis of the (a) Commentary to the GloBE Model Rules (b) Administrative Guidance to the GloBE Model Rules and (c) Safe Harbours before the start of the Fiscal Year.

Specific charging provisions are included to impose the tax on the relevant taxpayers, including how the tax is calculated and charged for joint ventures, minority owned entities and investment entities. It also provides joint and several liability for the tax amongst Constituent Entities in the Group rather than using the GloBE allocation rules and provides currency translation rules for payment of the tax. Adjustments are then made to the GloBE Rules, for example, to specifically exclude the rules relating to the UTPR provisions, to exclude provisions that are not relevant in the local context (e.g. rules relating to eligible distribution tax systems), and to align with the requirements for a QDMTT (e.g. by excluding certain taxes such as CFC taxes charged in a residence jurisdiction as being covered taxes). Some of these features draw on the ATAF Suggested Approach to DMTT legislation (available at https://ataftax.org/wp-content/uploads/2025/07/ATAF-Suggested-approach-2023-Low-res.pdf).

Incorporation by reference has been done using a static approach, where the reference is made to specific versions of the documents referred to in the first paragraph of this box. This is complemented with Section 23 of the GMTA which grants power for the Minister of Finance to add to the list of applicable Administrative Guidance new documents as they are agreed by the IF. Such new documents would be specifically added to the Government Notices in the Gazette. This feature allows for more control by South Africa, as well as more oversight of the Minister’s actions because such gazetted notices lapse at the end of the following year unless Parliament confirms otherwise.

1. Incorporation by cross-reference can be seen as giving up some level of sovereignty over the tax law making process, particularly if it is ambulatory. On the other hand, the GloBE Rules are designed as a common approach, so once the sovereign decision to implement is taken this should be done in a way that is consistent with the outcomes provided for under GMT, including in the light of Administrative Guidance agreed by the IF. Incorporation by cross reference allows jurisdictions to maintain alignment with the GloBE Rules automatically, i.e. without the need to further amend their own law. Because the GloBE Rules are a common approach, continued alignment helps ensure predictable and coordinated outcomes, and reduces the risk of inconsistencies emerging between jurisdictions. Under this approach, the decision to reference the Model Rules or Commentary remains a matter for the domestic legislature, which retains full discretion to modify or repeal the cross-reference at any time, and to any extent.

2. Some implementing jurisdictions that have repeated or rewritten all 10 of the Chapters making up the rules have nevertheless been able to incorporate by reference other elements of the rules, such as the Commentary or the Administrative Guidance (see discussion of Slovenia’s approach to incorporation set out in Box 7 below).

Box 7. S v ’ c c g G BE Ru (A bu y c f

changes to Commentary through a Cross-reference Approach)

Slovenia introduced an IIR, UTPR and QDMTT through Act on minimal taxation which provides for a transposition of the content of the Council Directive (EU) 2022/2523 of 14 December 2022 that provides for a comprehensive transposition of the GloBE Rules with the necessary adaptation to comply with European law requirements.

Article 3 of the Act stipulates that in the application of the global minimum tax (among others) the Commentary should be used in order to ensure consistency of the rules. This provision effectively incorporates the Commentary and any of its future updates by means of Administrative Guidance directly into Slovenian law. This incorporation of the Commentary and future Administrative Guidance by cross-reference ensures the legal framework of the Slovenian GMT is updated without the need for amending the primary legislation.

1. In general, incorporation by cross-reference is a simple way to achieve consistency with the GloBE Model Rules and the Commentary and to facilitate administration over time. In particular, it: • Keeps the cost of introducing the law to a minimum; • Minimises the risk of inconsistencies with the GloBE Rules (as well as between jurisdictions incorporating by reference); • Enables taxpayers and administrators to focus on complying with a single set of rules; • May reduce demand on administrators for early certainty mechanisms; • Facilitates the incorporation of future updates or changes agreed by the IF, which can be implemented automatically or through administrative procedures (rather than legislative amendments).

2. While different approaches of cross-reference method are illustrated in the examples above, each of them has its own benefits and drawbacks as presented in the table below.

Table 3. Comparison of ambulatory and static approach of cross-reference

2.1.2. Incorporation by repetition

1. Most jurisdictions consider that for them, incorporation by reference of all or parts of the GloBE Rules is not possible for technical or constitutional reasons. Incorporation by reference may conflict with a jurisdiction’s domestic legal principles, such as the exclusive competence of the Parliament to enact or amend tax law. Other jurisdictions have expressed the concern that incorporation by reference might also risk importing legal definitions that could create ambiguity or reduce the clarity of the law for practitioners or domestic courts.

2. Some jurisdictions have chosen to incorporate the GloBE Rules by reproducing an almost verbatim copy of the Model Rules in their domestic legislation. This approach generally seeks to replicate, as closely as possible, the GloBE Rules, with only minor adaptations to align with domestic legal conventions, terminology, and legislative hierarchies (“incorporation by repetition”). Beyond the translation necessary for jurisdictions where English is not an official language, these adaptations are typically intended to ensure legal coherence and effective administration within the domestic legal system, including with respect to procedural aspects such as investigation powers, assessment rights, and the imposition of interest and penalties.

Box 8. GMT Incorporation by Repetition in Malaysia

Malaysia legislated for the IIR and a QDMTT by adding a new Part XI to the Income Tax Act 1967 which replicates the language of the GloBE Model Rules almost verbatim into domestic law. In other words, the domestic legislation repeats the wording of the GloBE Model Rules with a few modifications.

This Part adds almost 130 pages to the Malaysian legislation, of which 32 are related to administrative matters. Because Malaysia is able to legislate in English, and to refer to monetary sums in foreign currency, the task of incorporation by repetition was easier. However, minor adaptations to the structure were still made. For example, definitions were moved to the start of the rules or to be part of substantive sections and cross references among different provisions had to be changed for them to fit into domestic legislation.

Under Malaysian law, any Agreed Administrative Guidance is deemed already incorporated in the Malaysian law and as such directly applicable and binding for the taxpayer, without the need to be transposed into Malaysian law. This is a result of the definition of “GloBE Rules” in subsection 157(1) read together with the scoping provision of section 158 of Income Tax Act 1967. This appears to be an ambulatory reference, so that future changes are automatically incorporated (see also para.4.19(b) of the Inland Revenue Board of Malaysia Guidelines The Implementation of Global Minimum Tax in Malaysia (2/12/24)).

1. This approach can also be coupled with: • use of secondary legislation to incorporate Commentary and Administrative Guidance that is not merely explanatory; • incorporation by cross-reference of the Commentary and Administrative Guidance, as in the Malaysian example described above.

2. This approach is intended to give as many of the benefits of incorporation by cross-reference as possible, for jurisdictions that are not able or wanting to use that technique. It will likely involve fewer legislative resources than a complete rewriting, and it will also tend to assist with consistency.

3. From a legislative perspective, jurisdictions seeking to repeat the Commentary and Administrative Guidance as well as the Model Rules will need to consider what provisions in the Commentary and other Administrative Guidance merely clarify the Model Rules (so do not need to be repeated) and what provisions are more substantive and therefore do need to be incorporated by repetition.

4. Jurisdictions that incorporate only the Model Rules by repetition and then incorporate Commentary and Administrative Guidance by reference do not have this issue. However, users will face the challenge of having to find the law in two different places. Some jurisdictions may also want to clarify whether the legislated Model Rules, or later changes to Commentary or Administrative Guidance which are incorporated by cross-reference, take precedence in the case of a conflict.

5. Jurisdictions where English is not an official language might have an additional limitation. The Model Rules have been officially translated into other languages, so incorporation by reference of those may be possible in a jurisdiction that can legislate in those languages. However, for those who legislate in another language, incorporating the Model Rules, Commentary or Administrative Guidance, would require a translation.

Box 9. Cross-reference to the English versions of the GloBE Rules in Liechtenstein

Although Liechtenstein usually enacts its legislation in German, it implemented an IIR and QDMTT through Article 2 of the Law of 10 November 2023 on the minimum taxation of large enterprise groups (GloBE Act) which makes a cross-reference to the English version of the GloBE Model Rules approved by the IF on 14 December 2021 which is published on the Liechtenstein’s Fiscal Authority website. By referring to the English version of the GloBE Rules, Liechtenstein sought to preserve consistency of interpretation with other implementing jurisdictions and to reduce the risk of divergence that could arise from translation, while the binding domestic legislation itself remains enacted in German.

Similarly, Liechtenstein ensures consistency with the English versions of Commentary and future Administrative Guidance through Article 2 of the Ordinance of 26 March 2024 on the minimum taxation of large enterprise groups (GloBE Ordinance), which provides that the GloBE Act shall be interpreted in accordance with the Commentary and any Administrative Guidance. The documents that have been released by the IF are also published on the website of the Liechtenstein Fiscal Authority serve as interpretation for the application of the GloBE Act.

Liechtenstein also published English versions of the GloBE Act and the GloBE Ordinance, however these translated versions are provided for information purposes only and have no legal force.

2.1.3. Full or partial rewrite of the GMT rules

1. Some jurisdictions have incorporated the GloBE Rules into their domestic law through a full or partial rewrite of the Rules (incorporation by rewriting). Under this approach, the Model Rules and (to the extent thought necessary) the Commentary and Administrative Guidance are rewritten to bring them into line with the domestic legal conventions, terminology and structure of existing tax legislation (typically, the legislative framework governing CIT). Some countries have done this entirely through primary legislation, but this method can involve the use of both primary and secondary legislation. In either case, it requires a thorough review of the translated or adapted rules to ensure that they deliver outcomes consistent with the GloBE Rules.

Box 10. Rewrite of the GMT rules in France

France introduced an IIR, UTPR and QDMTT through article 33 of the Finance Act for 2024 n° 2023- 1322 which provides for a transposition of the Council Directive (EU) 2022/2523 of 14 December 2022) which in effect provides for comprehensive transposition of the Model Rules with the necessary adaptation to comply with European law requirements The main adaptations refer to the use of a domestic IIR and the inclusion, within the scope of taxation, of purely domestic MNE Groups (i.e. large scale domestic groups).

In adopting the GMT, France was required to follow the Directive which effectively rewrites the GloBE Model Rules. The French legal system does not allow for transposition by reference (nor can a Directive be implemented by reference) which means that the GloBE Rules must be incorporated directly into French law. Under the rewrite approach, the provisions of the GloBE Model Rules, Commentary and Administrative Guidance are reformulated to fit into the French legal writing technique. This rewrite approach will also be used in future Finance Acts to incorporate any future Administrative Guidance in domestic law.

The primary legislation is supplemented by decrees (secondary legislation). On 4 December 2024, the French Government published the first decree dedicated to the GMT reform (decree n° 2024- 1126). It sets out the detailed compliance rules for France’s implementation of Pillar 2. It specifies reporting obligations for Constituent Entities, including the content of the GIR and procedures for calculating and paying the top-up tax.

1. The main benefit of this approach for many jurisdictions is that it is compliant with their constitutional/legal framework and constraints. This approach also allows for an easy integration within the domestic legal system (including domestic procedures for collection and enforcement). It can help a jurisdiction to develop a comprehensive understanding of the rules at an official and taxpayer level. It may also allow for the resolution of ambiguities identified through consultation.

2. Jurisdictions adopting the rewrite approach will need to assess their resource requirements. The rewrite approach is relatively complex and resource intensive to implement. It has the potential to create gaps, duplications and inconsistencies with the GloBE Rules, as domestic GMT rules will be drafted with a different structure, sequencing and terminology to the GloBE Rules. The jurisdictions adopting the rewrite approach also often do not allow automatic incorporation of future updates or changes agreed by the IF, meaning such updates will require the jurisdiction to determine whether, which, and how, domestic GMT rules need to be amended, and then where relevant to carry out the corresponding legislative process.

3. Under this approach, tax administrations should therefore be prepared to invest time and resources to ensure transparency, certainty and consistency in the practical application of the domestic GMT rules. This may include developing detailed administrative guidance and manuals, providing extensive staff training (to ensure familiarity with both with the GloBE Rules and the rewritten domestic rules), and invest in communication with taxpayers to ensure a common understanding of the domestic rules and their alignment with the GloBE Rules.

4. Recognising these challenges, several jurisdictions adopting a rewrite approach have also reported the use of complementary legislative and interpretive techniques aimed at mitigating inconsistencies and reducing compliance burden. These accompanying techniques are not mutually exclusive and are often used in combination to meet their objectives, as further described below.

Choosing an implementation approach: key considerations

Jurisdictions looking to choose an implementation approach will often need to consider a range of factors, which will vary in importance from country to country. As set out above, they include:

• Constitutional constraints; • Language requirements; • Domestic legal drafting conventions; • The Government resources required to implement and maintain the law; • The number of taxpayers affected and revenue expected; and • Their ability to enact the domestic law changes needed to keep up with changes to the GloBE Rules. • Their ability to introduce secondary law or administrative provisions to implement part of the GloBE Rules in a more expeditious manner.

2.2 Legislative techniques for updating domestic law

1. The GloBE Rules have seen significant development since their initial publication in 2021, with a number of packages of Administrative Guidance and Safe Harbours agreed. Implementing jurisdictions need to incorporate these developments into their own rules accurately, and on a timely basis, in order to maintain qualified rules and a globally co-ordinated system. In doing so, implementing jurisdictions have adopted different techniques to ensure their domestic rules include the latest updates. 2.2.1. Use of secondary legislation

2. In some jurisdictions, the executive branch has the ability to make legally binding rules, often only when delegated, and subject to judicial or legislatively imposed constraints or requirements. These deal with more detailed matters than those dealt with by primary legislation, and are often referred to as regulations or rules, as opposed to laws. This secondary legislation is often much easier to enact than primary legislation, and is an important part of the legal system in more regulated economies.

3. In some jurisdictions, only a limited number of core provisions – such as those defining in-scope taxpayers, the charging mechanism, and the ETR computation – are laid down in primary legislation. To facilitate timely incorporation of new Administrative Guidance, as well as to address gaps and inconsistencies identified in their domestic GMT rules and provide further details to the operation of the rules, these jurisdictions rely primarily or in part on secondary legislation for implementing the GloBE Rules.

4. This approach enables jurisdictions to take advantage of less burdensome amendment procedures that are applicable to secondary legislation (e.g. regulations), such as accelerated legislative processes or eliminating the need for separate Parliamentary approval, thereby allowing for faster updates when new guidance is agreed by the IF or inconsistencies need to be addressed.

Box 11. Use of Secondary Legislation in Brazil

Brazil introduced a QDMTT through a framework legislation (Law 15.079/2024) which incorporates the essential elements of rules in a manner that is consistent with Brazil’s constitutional framework. This primary legislation includes for example scoping provisions, the ETR and Top-up Tax calculation formulas as well as certain definitions provided under the GloBE Rules. Article 3 of the primary legislation authorises the regulatory body to adopt secondary legislation on the more technical and operational aspects of the DMTT. This led to the adoption of Normative Instruction 2.228/2024 which includes, among others, currency conversion rules, the adjustments made to determine the GloBE Income and Adjusted Covered Taxes of Constituent Entities located in Brazil, the computational provisions for the Substance Based Income Exclusion and rules relating to corporate restructurings and holding structures.

Brazil relies extensively on secondary legislation to implement a QDMTT because the GloBE Rules are technical, dynamic, and dependent on detailed calculations that cannot be fully codified in primary law without making it rigid or rapidly outdated. By passing a primary legislation that serves as a framework statute and delegating technical implementation to the regulatory body, Brazil ensures administrative flexibility to align domestic rules with future administrative guidance, achieve consistent outcomes with the GloBE Model Rules, and secure the regime’s recognition as a qualified DMTT. This approach allows the government to update methodologies, definitions, and compliance procedures efficiently while keeping the core legal authority anchored in legislation.

2.2.2. Simplified amendment procedure

1. To further facilitate regular and timely updates, some jurisdictions have also introduced provisions in their GMT legislation granting the Ministry of Finance or the tax administration authority to amend parts of the primary or secondary legislation by administrative instruments provided such amendments are necessary to ensure continued consistency with the GloBE Model Rules and the Commentary. This delegation of authority can significantly shorten the legislative process while maintaining legal oversight.

2. Some jurisdictions report using procedures allowing a taxpayer to rely on announced legislation or draft guidance prior to formal enactment, to provide greater certainty and facilitate compliance during transitional periods. This approach offers several practical advantages. It gives taxpayers administrative flexibility and reduces compliance risk during periods of uncertainty, while ensuring that once retrospective

Box 12. GMT Simplified Amendment Procedure in the United Kingdom

The UK has implemented the GloBE Rules by way of rewrite. The UK legislation generally puts the Model Rules, as well as the operative aspects of the commentary and administrative guidance which amend or expand the rules, into legislative language in legislation.

Section 262 of the UK Finance (No.2) Act 2023 gives His Majesty’s Treasury the power to make regulations that further make or amend its GMT provisions. This power may only be used where necessary to ensure consistency with the OECD model rules, Commentary and Administrative Guidance, and will terminate at the end of 2026. This power has not been exercised to date, with all amendments being made through primary legislation.

legislation is enacted, any required amendments can be made without penalties or interest, provided the taxpayer acted reasonably. It also promotes efficient use of resources, avoids unnecessary disputes over temporary positions, and gives taxpayers a degree of practical certainty even before the required amendments are made to the law.

Box 13. Ability in Australia to Rely on IF-level changes not yet enacted

Under the Australian legal system, taxpayers must self-assess their tax liabilities (and file a tax return) under the words of the current law. However, an inconsistency may arise between Australia’s domestic law and the OECD materials where Australia has yet to implement the agreed Administrative Guidance or if there has been a minor drafting oversight in the Australian law.

In order to address such inconsistencies, the ATO will apply practical guidance for the administrative treatment of retrospective legislation for taxpayers that ‘anticipate’ legislative amendments to address these inconsistencies, whether or not there has been a separate formal announcement from the Government. Practically, this provides taxpayers with more certainty in lodging the domestic tax returns on the basis of the OECD materials even if the domestic law has yet to reflect some aspects of the OECD materials.

If taxpayers choose to self-assess based on the existing (pre-amendment) law, and retrospective legislation is later enacted, such taxpayers will need to amend their assessments. In these situations, the ATO’s approach addresses any resulting interest and penalty consequences, typically remitting penalties where the taxpayer acted in good faith under prevailing law and seeks to amend their assessment, while still ensuring that the enacted law is ultimately applied.

If taxpayers choose to anticipate a future law change, the ATO generally will not direct compliance resources to check those self-assessments against the existing law (pre-amendments), as this would be inefficient. Where taxpayers anticipate a change, they should internally document the inconsistency identified between the Australian law and the OECD materials.

For GloBE purposes, this practically means the ATO would allow taxpayers to file the domestic Pillar Two tax returns (which in turn are based on the GIR disclosures) based on Administrative Guidance that has not been incorporated into Australian legislation yet. When that is the case, ATO will review what taxpayers filed based on their interpretation of the announced legislative amendments and actual amendments once enacted.

2.2.3. Interpretive clause

1. Many jurisdictions have also adopted an interpretive clause in their GMT legislation specifying that domestic provisions should, to the extent possible, be interpreted consistently with the GloBE Rules Including Commentary and Administrative Guidance. This reference can appear directly in the body of the primary law, or in the preamble or explanatory notes to the primary law. Such clauses serve to: • reduce the scope for inconsistencies or divergent interpretations, by clarifying that alignment with the GloBE Model Rules and Commentary is an interpretive objective unless there is a direct conflict; and • facilitate interpretations consistent with subsequent IF guidance, where the new guidance can reasonably be interpreted as a clarification rather than a substantive amendment requiring legislative change.

2. Even where the update to the Commentary does not necessarily operate as a mere clarification to the language of the Model Rules, the interpretation clause can allow the tax administration of a jurisdiction to interpret the domestic law in the light of this new update. Having such an administrative discretion and applying it, might prove more efficient than amending the primary legislation when updates to the Commentary go beyond clarifications.

3. Still, it is acknowledged that in many jurisdictions an interpretation clause will not automatically incorporate new Administrative Guidance and the administrative discretion with respect to the interpretation clause is accordingly more limited. In other jurisdictions, the legal tradition may mean that very similar clauses can have a more expansive effect.

Box 14. Interpretative Clause

Some jurisdictions (e.g., Canada) that have generally taken the approach of rewriting the Model Rules and Commentary into their domestic legislation also include an interpretive rule that is intended to ensure the legislation is interpreted, applied and administered in a manner consistent with the outcomes provided under the Model Rules, Commentary and Administrative Guidance, including any future revisions or additions to the Pillar Two Rules. For such jurisdictions, the question of how to give effect to new Administrative Guidance issued by the OECD will be determined on a case-by-case basis to determine whether specific legislative provisions need to be enacted or whether the Administrative Guidance can be applied to interpret or clarify the existing provisions.

1. Some of the jurisdictions have also introduced in their domestic legislation targeted crossreferences to specific provisions of the GloBE Model Rules and the Commentary. Through such references, the identified part of the GloBE Model Rules and the Commentary become an integral part of the domestic law, incorporated the same way as under the full incorporation by reference approach.

2. These targeted cross-references can also be designed to allow automatic incorporation of subsequent updates or amendments agreed by the IF to the identified provisions, in accordance with the ambulatory approach. Alternatively, under the static approach, incorporation of such future updates or amendments may be subject to a domestic approval procedure, such as an administrative act from the government.

3. Targeted cross-references can serve several practical purposes. For example, they can give timely and transparent effect to the rule order within a jurisdiction, by referencing the central record of jurisdictions with qualified status maintained on the OECD web site. Combined with an ambulatory approach, this can facilitate the recognition of qualified status of other jurisdictions without delay or need for legislative or administrative actions. Because the cross-reference is limited to a defined portion of the GloBE Model Rules and the Commentary – rather than the full set of GloBE Model Rules and the Commentary – this technique represents a pragmatic option generally available to a broader range of implementing jurisdictions (including those operating under more constrained constitutional or legislative frameworks).

Box 15. S g ’ T g d R f c OECD’ C R c d f Ju d c w Qualified Status

Singapore gives effect to the qualified status of other jurisdiction’s IIR, QDMTT and QDMTT Safe Harbour in line with the determination of the IF through Regulations 96 and 97 of the Multinational Enterprise (Minimum Tax) Regulations 2024. These provisions refer to the taxes imposed by each law of a jurisdiction set out in Central Record of legislation with qualified status published on the OECD website. The use of the ambulatory reference approach through secondary legislation allows Singapore to recognise the qualified status from the effective date of the applicable legislation when it is added to the Central Record after the effective date without releasing a separate list of qualified rules and without requiring further action by Parliament.

2.3. Interpretation mechanisms

1. Beyond the legislative process itself, implementing jurisdictions typically rely also on a wide range of non-legislative or interpretive instruments to encourage taxpayer compliance and achieve consistency with the GloBE Model Rules and Commentary. These instruments form part of the broader domestic legal and administrative framework and are typically used to clarify how domestic tax rules apply to specific facts and circumstances, and by doing so assist taxpayers with meeting their compliance obligations. While the nature and legal effect of such instruments vary considerably across jurisdictions, they typically take the form of guidance issued by tax administrations to interpret, supplement or operationalise domestic tax provisions (e.g. rulings, FAQs). In the context of the GMT, these mechanisms can be important in achieving consistency with the GloBE Rules and minimising compliance burden, especially for jurisdictions that have adopted a rewrite approach. Two broad categories of interpretation mechanisms can used to support the application and administration of the GMT (i) the issuance of public guidance, and (ii) the issuance of private guidance. 2.3.1. Public guidance

2. Many implementing jurisdictions have reported the use of administrative procedures that allow for the publication of official guidance on the application of their domestic GMT rules. Depending on the jurisdiction, such guidance may be non-binding, binding only on the tax administration, or may be binding on both the administration and taxpayers. Common examples include administrative guidance, general rulings (published in anonymized form), explanatory notes, circulars and ministerial instructions.

3. Irrespective of form, public guidance typically serves to clarify how specific provisions of domestic GMT legislation apply to defined facts and circumstances, particularly where a large number of taxpayers may be affected or where a provision has generated uncertainty in practice. It can be an efficient way to address gaps in the GloBE Model Rules and Commentary, incorporation inconsistencies between the domestic rules and the GloBE Model Rules and the Commentary (at least, on a temporary basis), as well as to support greater alignment in the application and interpretation of the GMT rules across jurisdictions and over time.

4. From a compliance perspective, such public guidance is also widely recognised as an efficient way to enhance transparency, certainty and predictability for taxpayers, thereby reducing disputes and overall administrative burden. In some jurisdictions, such guidance forms part of a broader dispute prevention and certainty framework handled by the tax administration. In others it results from a collaborative process involving multiple government bodies, such as the Ministry of Finance, legislative drafting committees and special technical bodies. In all cases, these procedures are generally designed to remain flexible and responsive, allowing tax administrations to address operational and interpretation issues raised by the application and administration of the GMT in a timely manner.

5. Public non-binding guidance is particularly valuable in the early stages of the implementation process, when taxpayers are still developing their understanding of how the new rules operate in practice and apply to their specific circumstances. Common examples include manuals or FAQs published on the official website of the tax administration, user guides or footnotes attached to reporting templates and online filing tools. These instruments are generally part of a broader communication strategy aimed at improving taxpayer readiness, reduce errors and minimise administrative burden (see Module 5).

6. Recognising the authority of jurisdictions to interpret and apply their domestic GMT legislation, jurisdictions may wish to ensure a consistent application of GMT rules across multiple jurisdictions through a coordinated interpretation of specific GMT provisions. Bearing this in mind, before issuing guidance, jurisdictions may find it useful to initiate discussions with other implementing jurisdictions on certain interpretation issues, for example through the Amsterdam Dialogue. 2.3.2. Private guidance

7. In addition, some jurisdictions reported using interpretation mechanisms whose legal effect is initially limited to one or a few taxpayers. Common examples include private rulings and written responses to taxpayer queries. The legal nature, criteria for availability and the binding effect vary significantly across jurisdictions.

8. Importantly, these mechanisms improve compliance and certainty for taxpayers. Depending on the legal framework private guidance, especially ruling, can offer more legal comfort to the taxpayers and their tax position. On the other hand, private rulings could result in less transparency among jurisdiction and thus risk inconsistent application of the rules. These risks are diminished where there is a programme of using private guidance as a basis for subsequent guidance being published for the benefit of all taxpayers (e.g. FAQs, general rulings) or where other transparency mechanisms are available.

Box 16. Good faith rulings in Austria

Individuals may request guidance by the Austrian tax authorities in the form of so-called “Good Faith Rulings”. A Good Faith Ruling is an administrative act by a tax authority presenting the legal opinion of the respective authority on the facts of a case described by the taxpayer. As opposed to formal advance rulings, Good Faith Rulings can be requested in an informal way and have more limited legal effect. However, based on court decisions, a Good Faith Ruling may be legally binding for tax authorities within the scope of their discretionary power if the following conditions are met:

• The Good Faith Ruling has been given by the competent tax authority. • The Good Faith Ruling is not obviously in contrast to the applicable Law. • The taxpayer has made economic arrangements based on the Good Faith Ruling. • A deviation from the Good Faith Ruling would be to the detriment of the taxpayer.

Box 17. GloBE individual Rulings in Poland

Poland has a special type of individual ruling tailored to the specifics of the GloBE (Tax ruling on top-up taxation). The National Tax Information Office issuing Tax ruling on top-up taxation may consult on a drafted ruling with the GloBE Council. The GloBE Council is a special advisory body, consisting of 11 qualified, independent experts from science, public administration, tax advisory and audit. Most of the experts come from outside the public administration. The Council was established to increase the participation of a broad range of public stakeholders in the interpretation of tax law. Collecting diverse perspectives and viewpoints, rather than relying solely on the administration’s perspective, is intended to ensure the proper application of the OECD/IF Common Approach.

Module 3. Organising and Planning for the Implementation of the GMT

Introduction

1. This module provides practical guidance for tax administrations on the practical changes for implementing the necessary process and resource allocation changes to administer the GMT. This guidance is based on a phased approach that begins with the development of a structured implementation plan which is then executed through various workstreams. Drawing on experiences of implementing jurisdictions, the first section of this module focuses on key elements to be considered in formulating an implementation plan, while the remainder considers the impact the GMT is expected to have on key administrative functions and examples of tools that tax administrations might use to facilitate the planning and execution of the changes that need to be made.

3.1. Implementation plan

1. An implementation plan is a structured roadmap that outlines how a change (such as a tax reform) will be implemented and made operational. It translates the high‑level policy or legislative reform into concrete steps to be undertaken by the tax administration and ensures that all relevant actors understand what needs to be done, by whom, when, and with what resources. A well-designed implementation plan can improve effective coordination across different units within the tax administration, support monitoring of progress, and reduce risk of gaps, bottlenecks, or delays.

2. The starting point in developing an implementation plan is to analyse the implications of the reform for the tax administration itself – particularly with respect to organisation, governance, operational processes, human resources, IT needs, and budget. A comprehensive implementation plan could include: • Objectives and expected outcomes that help clarify what reform is intended to achieve and the measurable results once it is operational. • Scope and priorities that define the parameters of the project as well as the key priorities which allow the tax administration to identify the impacted functions and the areas that require immediate or phased implementation. • Roles and responsibilities that define and allocate tasks across all relevant departments, units and teams of a tax administration that will be involved. • Timeline and milestones provide a schedule breaking down the implementation project into stages with key deadlines and expected deliverables. • Resource needs that quantify the additional resource requirements that will be needed over the short and long term. Resources include not only funding but should also address gaps in staffing, technical expertise, IT systems, and the legislative instruments required to support implementation. • Risk assessment and mitigation measures that identify potential challenges and the strategies needed to manage or reduce their impact. • Monitoring, reporting, and evaluation mechanisms that provide the tools to track, document and review progress helping ensure the rollout of the implementation plan stays on track. Key items could be captured on a matrix that can be updated on a regular basis to provide an overview of the current status of the implementation project (see box 18).

3. In practice the precise requirements of an implementation plan will be customised to the nature of the reform and the needs of the tax administration, with some areas requiring detailed advanced planning from the outset while others can be further planned later as the reform takes effect.

4. While tax administrations generally have experience in implementing tax policy reforms, there are a number of aspects unique to the GMT with a specific impact on the planning process. These stem from the fact that the GMT is based on a common approach and the need to ensure consistency with the rules of other implementing jurisdictions. This consistency extends from the domestic enactment of the rules in line with the Model Rules to how the substance of the rules is interpreted and applied in practice.

5. As well as a constraint, the common approach also creates an important opportunity in that jurisdictions that are adopting the GMT can build on the practical experience of those that have already legislated and implemented the rules. Early implementation experience — including administrative guidance, Safe Harbour approaches and systems adaptations — provides valuable insight into technical interpretation, compliance processes and risk management strategies, allowing later adopters to benefit from tested solutions rather than starting from principles.

6. At the same time, it is recognized that each implementing jurisdiction and tax administration starts its implementation journey from a different place. There are inevitable differences in existing legal frameworks, institutional capacity (IT, human resources, among others) and implementation design. Nevertheless, discussions in the Amsterdam Dialogue have highlighted a number of common challenges faced by tax administrations, including data collection and validation, systems integration, co-ordination between qualified domestic minimum top-up taxes and the IIR/UTPR, and managing compliance burdens for MNE Groups. More precisely, the meeting held on 11 April 2025 (“kick-off meeting”) of all the actions that lead to the drafting of this Toolkit identified four challenges in the context of the introduction and the implementation of the GMT: develop IT systems, ensure consistency in application and interpretation, build capacity and engage with stakeholders. Importantly, these discussions have also identified a range of practical solutions — from phased implementation and targeted guidance to enhanced inter-administration co-operation — demonstrating that, while approaches may differ in detail, shared experience can meaningfully support consistent and effective implementation across jurisdictions.

3.2. Assessing key tax administration functions and need for changes

1. Although tax administrations around the world have different structures, resources and operations, they tend to perform a similar set of core functions to ensure that taxes are assessed, collected, and enforced efficiently while supporting voluntary compliance. Below is an overview of the key generic tax administration functions that are common to many tax administrations. Tax administrations will need to identify which of these key administrative functions will be impacted by the introduction of the GMT, similar to what they may do when implementing any tax reform but considering the particularities of the GMT. For instance, the verification process might be different, and the exchange of information in the GIR in accordance with the dissemination approach will require adaptations.

Table 4. Overview of the key tax administration functions

Key Tax Administration Functions

3.2.1. Implementing possible organizational and administrative changes

1. Before designing or adjusting the administrative framework for the GMT, it is essential for tax administrations to carry out a thorough assessment of their operational needs. This begins with analysing what capabilities already exist—both in terms of teams and individual expertise—and understanding which units currently handle activities such as compliance, enforcement, assessment, customer service, and dispute resolution. Mapping these existing responsibilities helps identifying potential gaps and determine where additional support, new processes, or enhanced coordination mechanisms may be required.

2. A key consideration is whether current organisational structures are sufficient to manage GMT tasks or whether the creation of a dedicated coordination function is necessary. Given that multiple units— and in some cases other government agencies—will be involved, tax administrations are encouraged to consider establishing an advisory or steering body responsible for centralising design decisions, ensuring consistent interpretation of rules, and disseminating clear instructions across the organisation. Input for 32 For GMT purposes, a risk assessment framework will be the focus of Phase 2 of the Amsterdam Dialogue. this assessment may come from available data, internal interviews, or staff surveys, and may vary depending on whether the jurisdiction applies only a QDMTT or the full set of GMT rules. The size and characteristics of the in‑scope taxpayer population in a given jurisdiction also influence the scale of the organisational response.

Adapting Departments, Units and Teams for the Introduction and Implementation of the

GMT

1. How departments, units and teams are organised for GMT administration depends on the existing institutional structures and the choices outlined in the implementation plan. A thorough review of the tax administration’s organisational model—spanning compliance functions, collection processes, taxpayer services, assessment procedures, and audit activities—is necessary to understand how GMT responsibilities can be integrated effectively. This assessment helps determine which functions can be adapted and where new expertise or processes may be required.

2. In practice, tax administrations face two primary organisational choices: adapting existing departments, units and teams to incorporate GMT-related tasks or establishing new departments, units and teams dedicated solely to GMT implementation and ongoing administration. Each option carries benefits and challenges. Integrating GMT tasks into existing structures can support efficiency, continuity, and knowledge transfer, particularly where current staff already manage large business or international tax issues. Creating a dedicated structure on the other hand can help centralise expertise, provide clearer governance, and ensure faster development of specialised skills—though it may require additional resources. Two secondary choices can also be considered: create new sub teams within existing departments, units or teams or a matrix form (new central team with regional specialists).

3. The decision between these options should be guided by a range of domestic factors, including the size and complexity of the in‑scope population, available budget and resources, the administration’s chosen compliance and enforcement strategy, and the practical feasibility of recruiting additional staff. In some jurisdictions, recruitment may not be possible, making internal reallocation or reskilling the preferred approach. Regardless of the selected option, establishing clear roles, responsibilities, and communication channels remains essential for coherent and effective administration of the GMT. 3.2.2. Internal organisation: Governance and Resources

4. Drawing from the exchanges in the Amsterdam Dialogue workstreams, some experiences can be highlighted in terms of governance, cost and budget, and training of the workforce. Governance

5. Countries have adopted a variety of organisational approaches to implement GMT requirements, reflecting differences in administrative structures, institutional maturity, resource availability, and policy priorities. Although all tax administrations must deliver the same core functions—such as taxpayer services, filing and processing the returns, assessments, and auditing —the way these responsibilities are allocated can differ significantly. Some jurisdictions choose to embed GMT responsibilities within existing departments, units and teams, while others create new specialised departments, units and teams or transformation programs to manage the change.

6. The following examples (see box below) illustrate four distinct organisational options observed among implementing jurisdictions. They highlight how tax administrations can structure their teams, distribute responsibilities, build expertise, and coordinate internally to ensure effective and timely implementation of the GMT. These case studies are not prescriptive; rather, they provide practical insights into approaches that implementing jurisdictions have taken, the rationale behind those choices, and the types of functions or teams that can support successful implementation. The first two examples emphasize cases focused on implementation through compliance and transformation program, while the last two examples describe how tax administrations organised themselves for case handling.

Box 19. Four distinct organisational models observed among implementing jurisdictions Example 1 — Central Implementation and Compliance Team

In one jurisdiction, the authority has opted to create a central team dedicated to coordinating GMT implementation across the tax administration. This implementation team carries responsibility for the full set of administrative building blocks necessary for operational readiness. Core functions include overseeing IT development, ensuring that GIR and local tax returns can be filed on time, and establishing processes for taxpayer notifications. The team also coordinates GMT communications internally (across departments) and externally (with stakeholders and MNE Groups).

This central unit monitors relevant developments in international working groups such as WP11, WP10, LBIP and EU‑level initiatives, including Fiscalis. It appoints designated points of contact in other divisions, including the Large Business (LB) Unit and Exchange of Information teams, to ensure two‑way communication and coordinated implementation. Additional responsibilities include training delivery, progress reporting, and supporting interactions with businesses and stakeholders.

Example 2 — Transformation Programme Led by a Reform Directorate

A jurisdiction has placed responsibility for GMT implementation within a Directorate of the tax administration in charge of major tax reforms. This Directorate launched a comprehensive transformation programme that began by identifying all impacted functions—policy, legislative drafting, compliance, customer service, IT development, and others. The program produced a detailed implementation roadmap, mapped out the operational stages, and established a multi‑year budget (spanning five or more years), which was subsequently incorporated into the national Finance Bill.

The program started with a small cross‑functional core team, including IT specialists. An early task involved distinguishing processes or systems already in place that could be adapted for GMT from those that had to be built entirely anew. For example, the existing penalties‑charging system required only an extension, whereas registration and filing processes needed a completely new system dedicated to GMT. A specialised GMT compliance team was then created to support training, capacity building, and organisational readiness for GMT assessments and audits. This team’s responsibilities span from communications to IT coordination, to training design, to compliance activities (including risk assessment input), and to the rulings process.

Example 3 — Integration of the GMT into an Existing Large Business Unit

One jurisdiction has opted for a model, according to which the tax administration integrates all GMT responsibilities within its existing LB unit. The LB unit is structured into industry‑specific teams that already include both legal specialists and tax auditors. Within each team, several auditors have completed the GMT training program and act as the lead officers for GMT-related issues. While auditors do not dedicate their full time to GMT matters, legal experts do. These legal experts review auditors’ analyses and case files both during and after audits, ensuring consistency with previous interpretations adopted by the tax administration in comparable cases.

To address situations where legal experts and auditors diverge in their views, the administration has established a standing committee comprising the head of the LB division and two heads of unit. This committee is responsible for resolving internal interpretative conflicts. In parallel, a dedicated “predictive analytics competence centre” supports the development of risk filters for the GIR, leveraging its experience with high‑volume data processing.

Example 4 — Central Expertise Team Supporting General Case‑Handling Units

Another model adopted by some jurisdictions relies on a central team dedicated exclusively to GMT, while day‑to‑day compliance activities for large businesses remain within the regular case‑handling teams of the Large Business division. These frontline teams remain responsible for routine compliance work, including matters related to GMT, but can seek technical support from the central GMT team as needed. For small and medium‑sized enterprises, local tax inspectors maintain primary responsibility.

The administration has structured its GMT capability into three main support teams for both Large Enterprise and SME inspectors. First, the GMT Central Expertise Team comprises experts split between a central group and regional specialists. The central experts focus on IT, supervision, international developments, knowledge management, and general GMT issues, while regional experts serve as first points of contact for local inspectors. The team also emphasises internal cohesion and team‑building. Second, the GMT Knowledge Group is responsible for determining the tax administration’s positions on legal questions. Its issued and published viewpoints are binding administrative interpretations. Third, the Advance Tax Certainty Team, although not GMT‑specific, can draw on the expertise of the GMT teams when resolving advance certainty requests involving GMT aspects.

1. Together, these examples offer a reference for administrations considering how best to organise their own operational and governance frameworks for the GMT. They demonstrate that while structures may vary—from integrated models to centralised expertise hubs—clear coordination, role clarity, and investment in capability building are common features of effective implementation. Resources

2. When organising their framework and setting up teams, the tax administration should identify the resources available and necessary for the new governance. The aim is to allocate personnel to the dedicated units. This can be done through the reallocation of the existing employees or by recruiting new personnel.

3. Domestic factors should be taken into consideration. The amount of workload and in scope population is relevant and budgetary constraints can also play a role. The intensity of the compliance and enforcement choices will also have an impact on the choices. Cost and budget

4. Once operational requirements deriving from the GMT are clear, the next step is typically to project the financial and human resources necessary to carry out the reform. The objective is to secure the necessary funding and project management capacity.

5. The implementation plan outline will need to be translated into the investments required in people, systems and processes, over time. The focus may be on the immediate timeline for filing and exchange of the GIR and collection of top-up tax due. Maintenance costs also need to be considered: the continued compliance activities and maintenance of systems and processes after first filings and exchange will need to be taken into account as well.

6. From jurisdictions’ experiences, it appears that there is no “one-size-fits-all” approach. Jurisdictions with smaller in-scope GMT population and/or low-capacity jurisdictions seem able to manage the GMT implementation with just a few auditors and officers, while jurisdictions with larger in-scope GMT population and typically higher capacity, tend to have a higher number of auditors and officers. The number of staff assigned to the GMT can also depend based on whether the jurisdiction has a centralised or decentralised organisational model. In some jurisdictions, the officers and auditors retain their tasks related to other taxes, while taking on new ones related to the GMT. As such, the head count of officers and auditors does not necessarily reflect a full-time employee designated only to the GMT.

7. Associated costs of the investments required will need to be estimated to request for budget. Various factors will influence the level of costs: the size of the taxpayer population, the reliance on existing infrastructure, the labour market capacity and external versus internal hiring of staff, the communications and compliance strategy, and collaboration and synergies with other tax administrations. These costs will then be included in a request for budget which relies on domestic legal and administrative processes.

8. Arranging for monetary resources of the implementation project is essential to the successful execution of the implementation plan. As seen above, an initial estimation of resources is needed, including human resources and overall resources, to request and receive budget. Staff departments of the tax administration responsible for human resources and for oversight of implementation projects will be involved in the further arrangement of resources.

9. An example of considerations that all early implementing tax administrations encountered is whether to hire externally and/or internally, how to train (dedicated) tax officials on GMT rules, on GMT compliance, implementation, and auditing and what is the critical timeline and phasing of resources and deliverables.

10. The OECD has published many reports and guidance on designing and managing modern budget systems.³³ Focus on training

11. Training high‑quality staff is essential to ensure consistent and effective implementation of the GMT. Tax administrations should clearly identify the skills and knowledge required for each role and keep staff up to date as international rules and administrative guidance evolve. Training needs vary across teams: for example, compliance units may require only an overview of the basic functioning of GMT, whereas personnel responsible for risk assessment or audit activities need a deeper understanding of the full set of GMT rules and consolidated financial accounting. Many administrations have invested heavily in internal training programs, complemented by external expertise where needed—for instance, by hiring consultants with IFRS or financial accounting experience. Some administrations prefer to recruit junior staff and develop their skills internally, while others prioritize staff with prior experience in CIT or tax accounting. Regardless of approach, continuous learning and structured capacity‑building remain essential for preparing staff to manage new processes, conduct assessments, and provide support to MNE Groups.

12. The following examples (see box below) illustrate three jurisdiction-specific cases on trainings. 33 OECD (2023), OECD Journal on Budgeting, Volume 2023 Issue 1, OECD Publishing, Paris, https://doi.org/10.1787/c947ecd0-en. OECD Recommendation of the Council on Budgetary Governance — 2015: https://legalinstruments.oecd.org/en/instruments/OECD-LEGAL-0410. OECD Principles of Budgetary Governance — 2014: https://one.oecd.org/document/GOV/PGC/SBO(2014)7/en/pdf. OECD (2014), Budgeting Practices and

Procedures

in OECD Countries, OECD Publishing, http://dx.doi.org/10.1787/9789264059696-en.

Box 20. Three jurisdiction-specific cases on trainings Example 1 – Establishing a dedicated Training Unit

One jurisdiction established a dedicated Training Unit within the tax administration to organise and deliver GMT training. The Training Unit conducted high‑level information seminars open to all staff to raise general awareness of GMT. Selected officials also attended external workshops offered by international organisations such as the World Bank. Priority was given to staff responsible for the tax management of large companies within the Large Business Unit. Training for officials involved in international tax audits was scheduled for a later stage, as GMT audits were not expected to begin before 2027, and these trainings will include modules on tax accounting and consolidation. In addition, online training modules were developed for tax officers requiring only a general understanding of GMT—for instance, local teams managing smaller companies potentially in scope but not responsible for examining the GIR. Training content is tailored to each unit: while compliance units need only high‑level knowledge for mass handling of GIRs, control teams in both the large business and SME units require more advanced technical expertise.

Example 2 - Relying on Cross-functional Collaboration

Another jurisdiction relied extensively on OECD resources to train staff in the early stages. Building on this foundation, the tax administration’s policy team collaborated with the compliance unit to develop more detailed training materials aligned with the OECD Model Rules (MR), Administrative Guidance (AG), and domestic legislation. These included modular training packages, webinars, and written guidance. Training was provided not only to compliance teams but also to staff in other relevant units. To strengthen internal capacity, the compliance division hired personnel with experience in CIT for large businesses and supplemented these skills by recruiting external experts with accounting backgrounds, including specialists who are familiar with deferred tax assets.

Example 3- A staged-approach Training

A third jurisdiction initially focused training efforts on personnel with tax accounting expertise but later broadened its approach to include staff with general corporate tax profiles. As part of its long‑term capacity‑building strategy, the tax administration designed a one‑week, full‑time training program for new recruits. This intensive course must be completed before new staff begin operational work and serves as a foundational introduction to the GMT framework, related accounting principles, and the jurisdiction’s administrative processes.

3.2.3. External Communication to raise awareness of the GMT among MNE Groups and their service providers

1. To raise awareness of the GMT, communication actions toward MNE Groups and the service providers could be implemented. Reaching this goal requires identifying common building blocks and their specificity for the GMT, identifying objectives and corresponding actions, focusing on the taxpayer and their service providers, and using the proper channels.

Communication framework: common building blocks applied to GMT communication

1. While communication strategies should be tailored to the institutional context, legal framework, and administrative culture of each jurisdiction, experience shows that certain building blocks and good practices are common across most communication approaches adopted by tax administrations. Given the diversity of jurisdictional profiles, communication strategies should reflect differences in structures, economic size, taxpayer populations and interaction with other taxation regimes. The box below sets out a basic model for a communications strategy that is designed to address the specificities of the GMT.

Box 21. Communication Model

The model set out below is structured in six building blocks that can be applied to any major tax reform. At each step, the elements of the GMT are specifically considered

1. Identifying the audience: The first block concerns the definition of the communication strategies focus areas and audience for which tax administrations may consider obtaining input from other governmental entities related to the GMT implementation. This step could focus on mapping and segmenting stakeholders based on their roles, interests, and impact: MNE Groups, tax advisors, business associations, software providers, media, political leadership, and internal units (policy, compliance, audit, IT, HR, training). Segments where communication can materially reduce compliance risk or increase administrative readiness can be prioritised. Audience nuances need to be considered. For example, international advisory firms may already be familiar with GMT rules and require different communication strategies than those applied to in-scope MNE Groups and investors, depending on local context. As compliance for GMT may be centralised at head-office level, it can be advised to plan communications that target both headquarters and local compliance functions. Furthermore, the taxpayer’s audience can also be broken down. The communication strategy can be adapted to the needs of the ultimate parent entity (UPE), as well as the needs of local constituent entities. It can also be further refined considering the level of introduction and implementation: a QDMTT-only jurisdiction will convey a different message from a full GMT jurisdiction (implementing IIR, UTPR and QDMTT). 2. Understand the wider context for consistency and complementarity: GMT implementation is within a wider context and calls for consistency. It is recommended to leverage existing international guidance on GMT and to align domestic messaging to avoid duplication or inconsistencies. Domestic communication should focus on local design choices and areas where more detail is needed. Tracking international developments (e.g., administrative guidance, Safe Harbours, simplified ETR) could be useful to update communications accordingly. Considering the (transitional and/or permanent) peer review requirements would help to achieve consistency.

3. Identify topics / objectives of communication: Topics and objectives by rule and taxpayer profile. Objectives should be tailored to the rules introduced and sectors impacted: QDMTT versus IIR/UTPR, size and complexity of MNE Groups, and where compliance challenges are likely versus the quantum of top-up tax. 4. Identify channels and actions: Channels could be selected based on number and size of in-scope population and the scale of local operations. Advisory firms are often a core conduit. Jurisdictions with few UPEs may prefer one on one engagement while jurisdictions with many UPEs may rely on mass outreach (webinars, mail). 5. Communications plan / timeline: Building a time-phased plan aligned with GMT reform milestones will help. This timetable should specify for each action: officials and units in charge of each action, targeted audience, channels, required materials, and timeline. It is advised to formalise it into a dashboard to track execution status and issues (see box 1). The communication plan should be anchored with legislative timelines, GIR registration/notification, and filing dates, and expected dates of changes (e.g., Safe Harbours) as it is important to maintain transparency while allowing messages to evolve with guidance.

6. Evaluate effectiveness: Monitoring and evaluation of the communication plan against GMT objectives and specific outcomes is key to ensure its effectiveness and implement adjustments. Evaluation reports serve the purpose of informing and summarising the actions and outcomes and are also useful to analyse and summarise which of those actions were beneficial and which not. The final part of such reports can be dedicated to recommendations for improvement.

1. Among the identified stakeholders, engaging with the in-scope MNE Groups is paramount. Considering the variety of in-scope MNE Groups, the communication strategy can be adapted to their nature: UPEs and local constituent entities. The engagement can be as early as during the legislative procedure and/or public consultation. Such early communication does not only raise awareness of the GMT applying to these MNE Groups, but it also gives them basic understanding of the rules as intended to be implemented in that jurisdiction. On the other hand, it gives the opportunity for MNE Groups to provide their input and contribute to enhance clarity in domestic rules. Most importantly, the engagement with MNE Groups may help clarify technical questions and as such not only contributes to consistent application of the rules but also avoids and prevents disputes.

2. Communication strategy shall not be limited to MNE Groups. Tax administrations have developed a range of communication strategies to engage with external stakeholders, including in-scope MNE Groups, as well as with their service providers: tax advisors, business associations, strategy consultants and software and IT developers. Engaging communication strategies with the MNE Groups’ service providers helps to achieve the goals set as MNEs often use services of tax advisors to fulfil their compliance obligations. Some tax administrations even engaged with software providers and reported that engaging with IT service providers can help them to better understand the needs of the MNEs regarding the software they develop for compliance purposes as well as get familiar with the software the developers intend to provide to the MNEs.

3. Altogether, these strategies aim to improve stakeholder readiness by providing timely targeted information throughout the implementation and administration process. Their effectiveness seems to depend on how well they are tailored to specific audiences and aligned with key implementation milestones.

4. The message should be tailored to different stakeholders and consider the format in which the stakeholders are engaged with. To achieve that, the topics and audience should be considered when determining and applying the communication strategy. Depending on that, the tax administration should adapt the level of details and type of information that can be discussed and disclosed. For example, communication messages shall be different if they are intended for the UPE that is subject to the IIR in that jurisdiction, or for local Constituent Entities only in-scope of the QDMTT. In that regard, the number of UPEs present in a jurisdiction also has an impact on the type of engagement. A jurisdiction with a limited number of UPEs can develop an individual relationship with each UPEs and engage with them directly, while a jurisdiction with a significant population of the UPEs could prefer to use tools with a wider reach such as mass email campaign, specialised topic seminars or webinars (like for instance a presentation of technical elements as the Safe Harbours). The channels chosen should also consider the message the tax administration wants to send. For example, a one-on-one meeting can be tailored to specific facts and circumstances of a MNE, while a seminar with many MNEs attending should avoid disclosing individual tax data of specific taxpayer. The communication strategy should also consider the level of details to be conveyed. For instance, when engaging with service providers, details regarding the rules should be different when addressing with consolidation experts and with compliance service providers. Communication channels

5. A communication strategy can be executed through various means. Different channels (see Communication framework: common building blocks) could be used to target specific audience.

6. The following figure conceived based on the input received in the Amsterdam Dialogue presents possible communication channels that can help achieve different objectives and overall build trust and ensure compliance of the in-scope MNE Groups.

Figure 4. External communication objectives and channels

1. The use of behavioural insights can also be very efficient and increase the reach-out of communication strategies towards MNE Groups and their partners. Applying nudging techniques to encourage compliance and acceptance was proven effective to increase compliance. As part of the adaptation of the messaging to be done, frame messages to align with values and motivations of target groups can help. Testing and adapting messages using feedback loops and analytics is also recommended. 3.2.4. IT system and data handling

2. IT is essential to all aspects of tax administration and investment in software development often amounts to a large portion of the administration’s budget both in terms of capital expenditure (upfront costs) and ongoing maintenance. IT management and data handling have been identified by early implementers as a key function that is impacted by the GMT and requires careful consideration due to the large amount of data that will need to be received, processed and exchanged for compliance activities.

3. While some issues might be jurisdiction-specific, most IT considerations are the same for all jurisdictions that implement the GMT. Based on experience from early implementers, this section outlines best practices and practical considerations to support evidence-informed decision making and help jurisdictions in the planning and delivery of the IT infrastructure for the GMT.

4. The section is structured around three main building blocks: • Scoping identifies the key IT functionalities that tax administrations need to implement for the administration of the GMT. • Planning provides guidance on how to determine timeline and budget for adapting the existing IT infrastructure to the GMT. • Development approach illustrates some important factors when deciding whether to buy software solutions available on the market or build custom-tailored IT solutions. Scoping

5. Determining functionalities that IT systems need to perform for the application of the GMT and testing those functionalities against the exiting IT framework in the jurisdiction, is essential to estimate the scope of the IT development and produce the relevant budget proposal.

Figure 5. IT Functionalities for GMT Compliance

1. Experience from early implementers shows that the main IT functionalities for the GMT are: (i) user portal; (ii) information processing; (iii) information exchange; and (iv) Top-up Tax collection. These IT functionalities are the same irrespective of whether a jurisdiction adopts the IIR, UTPR and/or a QDMTT and tax administrations can either incorporate them in their existing systems or set up a standalone application for the GMT.

User Portal

1. Tax administrations are encouraged to put in place a user-facing portal that allows in-scope MNE Groups to file in electronic format any information they are required to produce, such as the GIR, a GMT return or the notification that the GIR will be received through exchange. Upon first access to the portal, each MNE Group can be provided with a unique identification number to be used for all future compliance activities.

2. If the domestic legislation requires MNE Groups to register and submit a list of their Constituent Entities, the portal should also permit the reporting of subsequent changes to the corporate structure.

3. Since the GIR is exchanged in Extensible Markup Language (XML), it is considered a best practice that local filing of the GIR is also required in XML to allow MNE Groups to follow the same format in all the jurisdictions where they operate. Jurisdictions that are new to group filing will also need to introduce a functionality that allows a single Entity (UPE, Designated Filing Entity or Designated Local Entity) to file the GIR on behalf of all other Constituent Entities of the same MNE Group that are located in the jurisdiction. For this purpose, systems could allow the classification of each Constituent Entity as “filer” or “not filer”, and permit changes from one Fiscal Year to another.

4. To ensure quality of the GIR data received, the portal should build in the file and record validation rules agreed by the IF³⁴ (and automatically reject the GIR filed by an MNE Group when that contains either file errors or sever record errors that would prevent the tax administration from opening and/or using the GIR).

Information Processing

1. When MNE Group information is received (either through local filing or exchange), IT systems must grant confidentiality and store data securely. To prevent inappropriate use, only the relevant personnel should be granted access rights and tax administrations should have in place tracking and record-keeping protocols that capture when the information is accessed and what it is used for.

2. As GIR information will generally be received in XML, tax administrations will need to develop a visualizer that translates it from machine-readable to human-readable format and insert the data in their client-handling system to improve accessibility for auditors and tax inspectors. To the extent possible, the tax administration could also consider the inclusion of automated risk filters that select or de-select MNE Groups for further control, increasing efficiency, limiting human intervention and ensuring better allocation of resources^35.

3. To identify possible gaps, tax administrations might seek to introduce automated checks that routinely compare the number of GIRs received with the estimated number of in-scope MNE Groups operating in the jurisdiction, and the number of GIRs received through exchange with the number of notifications received under Art. 8.1.3 of the GloBE Model Rules. To streamline compliance activities, software solutions can then be designed to automatically cross-check the information filed for GMT purposes with existing databases that might contain information on the same MNE Group (e.g. CIT, Country-by-Country Reports, chamber of commerce).

Information Exchange

1. The default mechanism under the GloBE Rules requires each Constituent Entity of the MNE Group to annually file the GIR in the jurisdiction where it is located. This local filing obligation, however, is switched off if the GIR is centrally filed by the UPE or a Designated Filing Entity in a jurisdiction that has a Qualifying Competent Authority Agreement in effect with the jurisdiction of the Constituent Entity. As not all implementing jurisdictions will need all the information contained in the GIR to administer their rules, the relevant portions of the GIR to be exchanged with each jurisdiction where the MNE Group is operating are mutually agreed as part of a Dissemination Approach.

2. Tax administrations need to implement the operational infrastructure and systems for the exchange of GIR information. This will include the development of an exchange file preparation tool that encrypts and compresses XML data when the jurisdiction is sending the GIR or decrypts and unpacks those data when the jurisdiction is receiving it. Jurisdictions that are already exchanging financial account information, country-by-country reports and tax rulings will need minimum adaptations to their existing systems, given that the GIR will be exchanged through the same channels (e.g. the Common Transmission System or the EU Common Communication Network). Any software solution, however, will need to incorporate the agreed validation rules (see paragraph 187), generate error messages (if any) and transmit those messages to the sending Competent Authority.

3. Existing EOI and transparency initiatives (e.g. CbCR) would normally require jurisdictions to exchange whole, undivided files. The dissemination approach, on the contrary, is specific to the GMT and 34 OECD (2025), GloBE Information Return (Pillar Two) Status Message XML Schema: User Guide for Tax Administrations, OECD Publishing, Paris, https://doi.org/10.1787/449e3cc3-en. 35 Phase 2 of the Amsterdam Dialogue will focus on developing a framework for Risk Assessment for the GMT. it would require tax administrations to exchange separate sections of the GIR with different jurisdictions based on their taxing rights. This can be done manually but, to facilitate exchanges within prescribed deadlines, the tax administration might seek to automate application of the dissemination approach through processes that would extract the jurisdictional sections of the GIR and produce different exchange files. As MNE Groups with the same Fiscal Year will file a GIR within the same deadline, to limit the number of exchanges, tax administrations might also consider IT solutions that would merge and exchange in bulk all the GIRs filed by different MNE Groups that need to be exchanged with the same jurisdiction.

Top-up Tax Collection

1. Before any Top-up Tax is due, tax administrations need to have systems in place to collect payments (as well as pre-payments or instalments, if any) and manage debt collection and application of interest and penalties.

2. Experience from early implementers shows that most jurisdictions are able to rely on existing CIT solutions for the collection of Top-up Tax, with little adaptations. The need for IT developments in this area is therefore expected to be limited.

3. When this is allowed under the relevant jurisdiction’s legislation, the software should permit a single Entity to pay Top-up Tax on behalf of the whole MNE Group. This might require changes to the existing IT payment infrastructure in those jurisdictions that do not contemplate the possibility of a single payer for CIT purposes (e.g. jurisdictions that do not have group taxation regimes). Planning

4. Most early implementers needed between 24 and 30 months to determine, design and deliver the IT solutions that were needed for GMT compliance. Leveraging this experience, however, IT planning (e.g. the determination of IT functionalities needed for GMT compliance) is expected to become quicker for jurisdictions that will implement the GMT in the future. In all cases, establishing a clear and realistic timeline is essential and tax administrations should start considering IT development as soon as possible, ideally before the legislation is enacted or becomes effective.

5. Communication and collaboration across different teams is of the utmost importance. A project lead should be appointed to co-ordinate different competencies and ensure that IT experts work closely with tax officials and auditors. Guidance from officials (either from the tax administration or the Ministry of Finance) that were more closely involved in the design of the legislation might be necessary on a case-bycase basis.

6. The first step in the process is a thorough assessment of the existing IT infrastructure, which will allow the tax administration to identify those functions that can be performed with minimum adjustments and those that need being purpose-built or more intensively restructured.

Box 22. IT Impact Assessment in France

France undertook in 2023 a comprehensive review of its existing IT infrastructure to enable informed decision-making with respect to functionalities that need being adapted or developed for GMT purposes. The study was also an opportunity to consider how the GMT implementation could support a broader rationalization and modernisation of their IT infrastructure.

The analysis examined how other IT projects could affect or delay the IT development for the GMT, and it aimed at relying to the extent possible on existing systems to limit costs and make the use of GMT functionalities easier for tax officials and MNE Groups. Language compatibility was identified as the main limit to take into account when assessing the possibility to integrate GMT functionalities within the IT framework of the jurisdiction (e.g. as the GIR is expected to be filed in XML format, it might not be possible to rely on existing filing and exchange of information (EOI) systems if they are based on a different mark-up language).

For registration purposes, France relied on the existing CIT filing portal with minimum adjustments that allow in-scope MNE Groups to register for the GMT.

It was necessary, however, to develop a new system for the lodging of the GIR because the GIR is the first return that is filed in France in XML format (and using the XML format for local filing is essential to facilitate further exchange of GIR information). Similarly, a new EOI system was developed because the existing one was found obsolescent and unfit for some GMT specificities (e.g. dissemination approach).

For Top-up Tax collection, treasury and debt enforcement, France was able to rely on existing systems for the management of corporate income tax payments.

1. Based on the IT impact assessment, the tax administration would then prepare an accurate budget proposal and submit it for approval. This should consider also the need for ongoing maintenance and longterm support in the use of IT systems after they are delivered.

2. Experience from early implementers shows that the estimated budget for the IT development is below EUR 15 million in most jurisdictions, with a significant portion of those jurisdictions (e.g. those with a lower in-scope population) having an estimated budget between 1 and 5 million. Drawing on the IT systems introduced by early implementers, however, jurisdictions that will implement the GMT in the future are likely to face lower costs (especially as more ready-to-use IT solutions will become available on the market).

3. After the budget is approved, IT experts would need to translate the IT functionalities that are needed for the GMT into technical specifications that IT developers can use for delivery. The design of the IT systems should provide enough flexibility to accommodate future Administrative Guidance that might be issued by the IF (e.g. changes to the XML Schema for the filing and exchange of the GIR).

4. To improve efficiency, the delivery of different components can be phased over time (e.g. the user portal will need to be finalized before GIR exchange systems). In any event, enough time should be allocated after the delivery of each component to test it before launch. The tax administration, for instance, might seek to develop a mock GIR to ensure correct functioning of the filing and exchange systems before any GIR is due.

Box 23. Planning for IT development in the Republic of Korea

The Republic of Korea implemented the GloBE Rules in December 2022, with the IIR becoming effective as of 1 January 2024 and the UTPR as of 1 January 2025.

The National Tax Service (NTS) started developing a strategic plan for the IT development in 2023. Their budget proposal, which considered the need to continuously secure appropriate resources for IT maintenance, was approved in late 2024.

The NTS developed a tentative timeline with the objective of having all the IT functionalities up and running before June 2026 (i.e. the deadline for the filing of the GIR with respect to 2024). Their milestones were set as follows:

• Public procurement process for the selection of an external contractor (January-April 2025) • Design of technical requirements (May-July 2025) • IT system development (August 2025 – January 2026) • Stabilisation, testing and launch (February 2026 – June 2026)

In preparing their budget proposal and strategic IT plan, the NTS considered all specificities of the GMT (e.g. Group reporting, high volume of data to be processed, dissemination approach for the exchange of GIR data, XML filing) and hired external consultants (i.e. accounting firm and law firm) to confirm that their IT systems met financial and legal requirements.

Development approach

1. To address their IT needs for the GMT, tax administrations can either build custom-tailored solutions or seek to purchase commercial-off-the-shelf (COTS) solutions. Experience from early implementers shows that a large majority of jurisdictions developed their own systems, while only a few jurisdictions relied on a readily-available-software. As the GMT is a novelty, however, this trend might change over time as more jurisdictions implement the rules and more IT solutions become available on the market.

Custom-tailored solutions

1. Custom-tailored solutions can be developed internally or outsourced to external providers when the tax administration lacks internal expertise or capacity to develop IT systems under tight deadlines. A combined approach is also possible, with some elements built in-house and others delivered by contractors. As they are built specifically for the jurisdiction, custom-tailored solutions generally provide higher flexibility and can be more easily integrated within the existing IT infrastructure.

2. Designing and developing new software, however, would generally require more time, as well as greater engagement from a larger team. Overall costs are more difficult to estimate, and any deviations from the original project are likely to result in schedule overruns and hidden expenses. Risk of failure is also greater because the proper functioning of each component can only be evaluated after that component is completed.

COTS solutions

1. COTS solutions are generally more affordable, they can be implemented within a shorter timeframe and might offer a cost-efficient approach, especially for those jurisdictions that expect lower Top-up Tax revenues due to the reduced number of in-scope MNE Groups that are headquartered or operating within their territory. They can be tested before purchase, and the vendor might be held liable for hidden defects or malfunctioning. COTS solutions, however, would typically offer a lower degree of customisation and they might be difficult to source on the market.

2. COTS solutions are expected to become more widely available in the future since software developers will be able to build on the IT systems meanwhile introduced by early implementers.

Box 24. The use of a COTS solution for the GMT in Denmark

Denmark implemented the GloBE Rules in October 2023, with the IIR and the QDMTT applicable to Fiscal Years commencing on or after 31 December 2023, and the UTPR applicable to Fiscal Years commencing on or after 31 December 2024.

After establishing the IT functionalities needed for compliance with the GMT, the Danish Tax Authority (DTA) asked other Member States of the European Union what approach they were following for the development of IT systems (including allocated budget) and started market research for readily available IT solutions. Sourcing principles included a price cap of EUR 6.67 million, delivery responsibility on the external supplier, ongoing maintenance and possibility of further developments to the systems after their launch.

Between October and November 2024, the DTA discussed details with four suppliers that presented their approach to an IT solution for the GMT. Dialogue focused on: (i) presentation of their standard systems; (ii) technical clarifications; (iii) timeline for implementation; (iv) operation of the solution; and (v) price indication.

In early 2025, the DTA launched a public tender with a pre-qualification that allowed three suppliers to participate. A first bid was presented in June 2025, and the DTA’s evaluation took into account also a product demonstration from the bidder. Following negotiations and a second bid in October, the contract was awarded in December 2025 and the implementation started in early 2026.

Best practices on IT system and data handling

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes the following guidelines for best practices on IT system and data handling, for GMT implementation: • Provide MNE Groups with a unique IT identification number to be used for all future compliance activities. • Ensure the user portal allows a single Entity to file the GIR on behalf of the whole MNE Group and permits changes in the classification of a Constituent Entity as filer or not filer from one Fiscal Year to another. • Incorporate agreed file record and validation rules to ensure quality of the GIR information received and exchanged. • Introduce procedures that ensure confidentiality and appropriate use of the information received. • Require local filing of the GIR in XML format. • Ensure that IT solutions allow a single Entity to pay Top-up Tax on behalf of the whole MNE Group (if allowed under domestic legislation). • Limit human intervention and increase automation over time (e.g. matching of GMT information with existing databases, risk filters, dissemination approach). • Start considering IT as soon as possible, and ideally before the legislation is enacted or becomes effective. • Appoint a project lead that supervises all teams involved (e.g. tax officials and IT experts) and ensures efficient communication and co-ordination among them. • Establish a clear timeline for the delivery of the different IT components, taking into account that some components (e.g. user portal) might need to be completed before others. • Provide for post-delivery maintenance and support in the budget proposal. • Allocate enough time for the testing of each component before its launch.

Module 4. Framework on Compliance Procedures

Introduction

1. The GMT operates as a common approach, meaning that IF members that decide to adopt the rules have committed to implement and administer them in a way that is consistent with the outcomes provided under the GloBE Rules including the agreed rule order. Consistent application and administration of the rules improves transparency, ensures a level playing field, eases coordination among implementing jurisdictions and reduces compliance burden.

2. While the Model Rules and the Commentary do not lay down every aspect of the operation and administration of the rules, the compliance framework should be designed in a way that preserves the benefit of the common approach and ensures consistency in the compliance and application of the rules. In setting out this compliance framework, references to the Model Rules, the MCAA and other IF standards are not intended to modify the application or interpretation of those standards and guidelines for best practices should only be applied in a manner consistent with those standards.

3. At the same time, tax administrations will have different starting points for their GMT implementation journey. Aside from differences in the taxpayer base, there are differences in legal systems, compliance culture and approaches, capacity, degree of digitalisation, timelines and differences in implementation options under the GMT. In this context, discussions within the Amsterdam Dialogue helped to identify common issues, considerations and best practices that can support jurisdictions in designing effective compliance procedures while limiting administrative burden and compliance costs for both tax administrations and taxpayers. The discussions also highlighted tax administrations’ interest in simplification and efficiency in the design and operation of compliance processes. While greater alignment in processes and timelines may also generate efficiency benefits, the feasibility of such alignment will necessarily depend on domestic legal and administrative constraints which vary across jurisdictions. These best practices aim to help promote greater consistency and coordination across jurisdictions, supporting the broader objective of a consistent and coordinated implementation and application of the GMT.

4. Building on the experiences of implementing jurisdictions, this Module identifies key compliance steps and sets out best practices on the design of the domestic compliance procedures in light of the particular challenges that tax administrations face. These best practices can support jurisdictions in the early stage of their implementation process with designing their core compliance requirements or, for jurisdictions that have already implemented the rules, they may provide guidelines in refining and improving their existing compliance requirements.

5. The Module first provides an overview of the steps included in GMT compliance procedures. It then analyses each step of the compliance procedure to help identify best practices that are summarised in a designated box after each subsection.

4.1 GMT Compliance procedures and best practices

4.1.1. Overview of the GMT compliance procedures

1. Recognising the novel and distinct nature of the GMT, most implementing jurisdictions provide for a compliance framework that is distinct from the one established for CIT purposes. While the steps of the compliance procedures resemble those under CIT, they are nevertheless separate from (and apply after the determination of) CIT creating separate obligations on in-scope MNE Groups.

2. The GMT compliance procedures are generally structured around four key steps: (i) the GIR and related notification; (ii) the GMT return(s); (iii) the payment of the top-up tax; and the (iv) penalties and other enforcement tools with respect to upfront compliance. In some cases, jurisdictions have also introduced a separate registration requirement for MNE Groups within the scope of the GMT, which generally precedes other filing obligations and helps identifying in-scope MNE Groups for administrative purposes. The structure of a typical GMT compliance process is illustrated in Figure 7 below.

Figure 6. Key Steps of the GMT Compliance Procedures

1. As set out in the figure above, the first step in the compliance process may begin with the registration. The registration supports the tax administrations to identify in-scope MNE Group operating in their jurisdiction. In some jurisdictions registration also serves as a mechanism that establishes a single point of contact for subsequent compliance requirements.

2. The GIR (and related notification) provides for a single information return in which the MNE Group is required to provide information on GMT calculations for all its Constituent Entities across the group. It contains a full data set relevant for calculation of the top-up tax liability and is as such the most comprehensive data source of information under the GMT. The information provided in the GIR is then exchanged and sent to all jurisdictions with taxing rights with respect to that MNE Group. Once received, the tax administration can use this information to perform an appropriate risk assessment and to evaluate the correctness of a CE’s tax liability under the GloBE Rules.

3. The GMT return is a separate obligation which like any tax return establishes the tax liability and the payment obligation on the MNE Group. Payment of the top-up tax liability is in most jurisdictions designed as a separate compliance step. It usually follows on or shortly after the filing deadline. Finally, the compliance process also includes penalties that incentivise compliance with respect to the GMT filing and payment obligations. Taken together, these steps form the upfront compliance procedures for GMT.³⁶

4. To ensure that the upfront compliance is as simple and effective as possible, a fully digital compliance process is strongly advisable. In recent years, a fully digitalised compliance process has 36 This section does not address investigative powers and more specifically the GMT risk assessment framework under the Phase 2 of Amsterdam Dialogue. emerged as a cornerstone of modern tax administration and such a digitalised compliance process is particularly crucial for the GMT, which involves the consolidation and exchange of large volumes of data maintained across multiple jurisdictions. Efficiency and accuracy therefore largely depend on enabling MNE Groups (typically, the single filer acting on behalf of the all the local entities belonging to the same MNE Group) to complete the entire compliance process digitally, including registration, notification, filing of the GIR and GMT returns, and payment of liabilities.

5. Recent experiences from some implementing jurisdictions demonstrate that it may be possible to design compliance requirements that are: • Fully paperless – with no requirements for physical signatures, certifications, or document stamping; • Accessible and user-friendly, ideally accompanied by clear user and practical examples; • Integrated into a single online portal serving as a “one-stop-shop” for all domestic GMT-related interactions, from filing to payment and corrections; and • Allowing third parties (e.g. advisors, software providers, agents) to submit filings on behalf of MNE Groups. It is acknowledged that the development of such compliance requirements is subject to domestic legal and operational constraints and depends on the administrative capacity and digital maturity of a given jurisdiction. Where digital solutions are not yet available and fully operational, the MNE Group should be able to meet its compliance requirements in an alternative manner.

6. These digital solutions have been reported to improve the accuracy and timeliness of filings, reduce administrative costs, and facilitate compliance by in-scope MNE Groups whose usually seek to coordinate and streamline GMT compliance from a central team within the MNE Group. Within the Amsterdam Dialogue, stakeholder representatives have emphasised that publishing filing templates, schemas, and portal specifications as well as making the online portal accessible at least 90 days ahead of the filing deadline is usually necessary for proper preparation of the returns and testing of the system.

7. It is recognised that for tax administrations developing, testing, and deploying these systems within tight timelines is resource-intensive while setting it up. Still, in the long-term having a fully digital compliance process substantially reduces burdens for both tax administrations and MNE Groups. 4.1.2. Registration

8. In some implementing jurisdictions, the first formal interaction between the tax administration and the MNE Group under the GMT framework takes the form of a registration requirement that generally precedes the first GIR deadline by several months – typically between five and ten months ahead of the GIR deadline. Purpose and format

9. While a registration step is not required under the GloBE Rules and has not been adopted by all implementing jurisdictions some implementing jurisdictions have introduced registration requirements as a preliminary step to assist their tax administrations in identifying their in-scope MNE population (see Module 1) and to facilitate the compliance process by allowing for the assignment of an identification number to all local constituent entities, including those that are not otherwise registered for CIT or VAT purposes. Some tax administrations propose to use this common identification number in the development of IT systems, taxpayer account management, and later compliance and enforcement activities.

10. In many cases where registration is required it is used to designate the single filer that will act on behalf of the MNE Group for all GMT compliance obligations in the jurisdiction, which enables the tax administration to establish a clear and direct communication channel early in the compliance process.

11. The value of introducing a registration process may also depend on the availability and reliability of existing data sources, and on each jurisdiction’s administrative costs of creating and maintaining a separate registration system solely for GMT purposes. Half of jurisdictions reported that they were able to rely on existing data sources to identify their in-scope taxpayer population, especially the CbCR data which provides comparable and reliable information on MNE Groups and their constituent entities (for more details, including on the appropriate use of the CbCR data see Module 1). Other tax administrations were able to rely on existing information and TINs in the development of their IT systems and compliance processes. Those jurisdictions therefore considered that a separate registration step was not necessary, noting that detailed information on local Constituent Entities would in any case be available through the GMT return and the GIR.

Box 25. Example – Au ’ c u c f f

To assess the population of in-scope MNE Groups and have an initial estimate of compliance resources required, Australia first relied on existing tax data. Corporate income tax returns were a key starting point as they include an indicator for large taxpayers. Through this process, the Australian tax administration estimated that approximately 3,000 firms may potentially fall within the scope of the GloBE Rules. Where information on the headquarter jurisdiction was missing, the tax administration manually verified the data to improve the accuracy of the estimate.

This approach based on tax return data was complemented by data from Country-by-Country reports, which were used in parallel to cross-check the estimation of the in-scope population. Additional sources of information were also considered by the Australian tax administration to improve the assessment. Financial statements were reviewed, as some MNEs disclose if they are in scope of the GloBE Rules and if they anticipate material top-up tax liability.

They compared the costs of introducing the registration process and the accuracy of estimates of the in-scope population on the basis of existing data sources. Australia concluded that the marginally increased accuracy that the registration would bring does not offset the costs such a process would incur. Therefore, they decided to not introduce a registration requirement.

1. Where registration is introduced, it is generally viewed primarily as a prediction tool – allowing tax administrations to obtain basic information on in-scope MNEs earlier in the process – relevant during the initial implementation years, when data on MNE Groups is still incomplete. Consistent with this, most jurisdictions that introduced registration have made it a one-off requirement, meaning only one time per MNE Group, usually when it comes into scope of the GMT. The in-scope MNE Groups only need to update the information when changes occur (for example, a change in the group’s UPE). Only a few jurisdictions require annual registration. In these few cases, in-scope MNE Groups are typically permitted to confirm that no changes have occurred since the previous year by simply ticking a box, thereby avoiding unnecessary repetition. Information required

2. Experience from implementing jurisdictions shows that the registration process can remain simple and effective if it focuses strictly on information needed to identify the MNE Group and the relevant single filer. A concise registration template is thus encouraged, collecting only key information such as: • The name and tax identification number (TIN) of the filing Constituent Entity, and relevant contact details; • The name, TIN, and location of the entity filing the GIR (typically the UPE or Designated Filing Entity), including contact details; and • The names and TINs of any other Constituent Entities located in the jurisdiction whose obligations will be met by the filing Constituent Entity.

3. Some jurisdictions do not require information on the identity of all local Constituent Entities, recognising that such information will become available once the GIR is submitted locally or received through exchange of information.

4. Further, experience shared by several jurisdictions indicates that the registration form does not need to include proof that an MNE is within scope of the GMT, nor should it request information subsequently provided in the GIR.

5. An MNE that is fulfilling its compliance obligations can reasonably be presumed to be in scope. Requiring proof or early data submissions may be burdensome for MNE Groups while yielding limited administrative benefits. Especially, collecting financial or group-level data duplicative with the GIR at registration and requiring such information well in advance of the GIR (typically five to ten months before the GIR is filed) can lead to low-quality or inconsistent data, since the MNE Group will not yet have completed its internal review or finalised its top-up tax calculations.

6. Examples of information that should generally be avoided at the registration stage because they duplicate GIR content and create unnecessary compliance burdens include: • Group-level financial data; • Presentation currency or accounting standards used by the UPE; • Information on foreign constituent entities (other than the UPE or the filer); • Top-up tax liability in the given jurisdiction; and • Elections made by the MNE Group under the GloBE Rules, including application of the Safe Harbours.

7. Nevertheless, jurisdictions might consider useful to provide an additional data point in the registration enabling the MNE Group to notify the jurisdiction of the MNE’s Group election for the SbS or UPE Safe Harbour.

Box 26. Example - Registration Process in the United Kingdom

In the UK, in-scope MNE Groups are required to register with HM Revenue and Customs (HMRC) within 6 months of the end of their first accounting period. There is a single registration which covers the whole of the MNE Group and applies for the UK’s IIR, UTPR and QDMTT. The registration only needs to be completed after the MNE Group’s first accounting period and helps HMRC to identify the in-scope population and set up the IT records so MNE Groups can file their returns and pay any Top-up Tax liabilities.

A single member of the group is responsible for completing this registration and does this through an online service. The registration process has been designed to be as simple as possible and only requires the minimum amount of information HMRC needs to administer the taxes (e.g. the name and address of the Ultimate Parent Entity, contact details for the group and details about the MNE Group’s accounting period). HMRC estimates this process takes 10-15 minutes to complete.

Deadline for registering

1. Where jurisdictions have introduced a registration requirement, in general, the registration serves the purpose of identifying in-scope MNE Group operating in that jurisdiction. As such, those jurisdictions consider that receiving this information is needed in-advance and therefore a deadline for registration usually follows shortly after the end of the MNE Group’s Financial Year, e.g. 5-6 months after the end of the MNE Group’s Financial Year. A few of those jurisdictions even require the registration as early as the beginning of the MNE Group’s Financial Year or the last day of the MNE Group’s Financial Year. This approach is strongly discouraged, especially since throughout the MNE Group’s Financial Year an MNE Group’s structure and thus its Constituent Entities and their location can still significantly change, therefore rendering the information provided in registration inaccurate. Where registration is required, it is encouraged that it is prescribed only as a one-time requirement, with an obligation for the company to report any subsequent changes or updates and an annual “check a box” when nothing changes so to confirm that the group structure remained the same.

Best practices for Registration

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit identifies the following guidelines for best practices for GMT registration: • Assess the need for registration. Review if registration is necessary considering whether existing sources of information are sufficient and reliable to identify in-scope MNE Groups and whether an identification number is required for a single filer. If there is a limited need for and benefit from registration avoid requiring registration. •

If a registration requirement is necessary, require only essential information that does

not require calculations. Where a separate registration is introduced, only request information that is necessary to identify the group and its filer – typically, the identification of the UPE (or DFE where relevant) and of the filing entity (where different from UPE), including related contact person(s). Further:

o Do not require MNE Group to prove they are in scope as part of registration; filing compliance forms should be sufficient proof. o Avoid requiring information already provided in the GIR, such as group financials, accounting standards, elections, or foreign entity information. o Require registration only one-time per MNE Group, with an obligation for the MNE Group to report any subsequent changes or updates. If annual registration cannot be avoided, allow companies to simply confirm (“check a box”) when nothing has changed since the prior year. • Registration after end of the MNE’s Group Financial Year. Avoid requiring the MNE Group to register before the end of the MNE Group’s Financial Year since the formation of the MNE Group and thus Constituent Entities might still change. • Online registration. Enable online registration, preferably through the same portal as subsequent filing of the GMT return. • Single registration. Allow for one Constituent Entity to register on behalf of the in-scope MNE Group.

4.1.3. GIR and related Notification

1. The GloBE Model Rules provide for the development of a standardised GIR that contains the information a tax administration needs to perform an appropriate risk assessment and to evaluate the correctness of a Constituent Entity’s Top-up Tax liability. A GIR is not required to be filed locally where the UPE or (a designated filing entity) has filed the return in another jurisdiction, which has entered into an exchange relationship with the local jurisdiction under the MCAA.³⁷ Where the MNE relies on this central filing mechanism to fulfil its filing obligations, a local Constituent Entity of the MNE Group must notify the tax administration in their local jurisdiction. This notification informs the local tax administration that the GIR will be received through exchange of information from the tax administration where the GIR is filed and as a result turning off any local GIR filing obligation. To further support GIR central filing the Inclusive Framework has also developed a notification template which simplifies and standardises the information required to notify a tax administration that the GIR will be filed centrally. This notification template requires the local Constituent Entity to report only: • the identity of the entity that will file the GIR (the UPE or DFE); • the jurisdiction in which the filing will occur; and • confirmation of the active status of the exchange relationship with that jurisdiction.³⁸

2. Several jurisdictions have also made the notification a one-off requirement, requiring updates only when relevant information changes (e.g. change in the UPE or central filing jurisdiction). Where domestic legal frameworks require annual notifications, in-scope MNE Groups are typically permitted simply to indicate that no changes have occurred since the previous year by ticking a confirmation box. Information required in the GIR

3. The GIR contains the information which has been agreed by the Inclusive Framework as being necessary and sufficient for a tax administration to perform an appropriate risk assessment and to evaluate the correctness of a Constituent Entity’s Top-up Tax liability. In developing the data points and explanatory guidance that are used for the GIR, the IF has sought to strike a balance between providing tax administrations with the data they need to undertake adequate compliance activities, while limiting the cost of compliance for MNE Groups.

4. Nearly all implementing jurisdictions have also developed – or are in the process of developing – online filing portals to enable electronic submission of the GIR in XML format, using templates aligned with the GIR XML Schema and user guide agreed by the Inclusive Framework. Common adoption of this schema, together with effective application of the common GIR validation rules, will be instrumental in supporting efficient automatic exchanges of the GIR through the Common Transmission System (CTS) and interoperability across systems (see Module 5).

5. The above considerations are focussed on the information to be provided under the GIR and the corresponding notification requirements under the central filing procedure. These considerations are most relevant to jurisdictions that have adopted an IIR (or UTPR) given the expected importance of the central filing and information exchange framework for these rules and the detailed requirements set out in the GloBE Rules and Commentary. This also applies to QDMTT-only jurisdictions that decide to enter in the central filing framework.

6. A different set of considerations may apply in the context of QDMTT-only jurisdictions that decide to require the GIR information to be filed locally and not enter into agreements to receive the GIR information through information exchange. These jurisdictions will typically already have mechanisms to access the tax and financial information on the Constituent Entities that are within the scope of the QDMTT. Notwithstanding these existing mechanisms, the GloBE rules do incorporate certain requirements on the 37 For more information on Central filing see Module 5. 38 The MNE Groups can access this information on the List of activated exchange relationships available at OECD (2026), Activated exchange relationships for the automatic exchange of GloBE information https://www.oecd.org/en/topics/sub-issues/international-standards-on-tax-transparency/automatic-exchange-ofinformation-exchange-relationships.html. information to be collected by QDMTT jurisdictions. That is, QDMTT jurisdictions may follow a different format from the GIR, but as the QDMTT would use equivalent data points to those provided in the GIR, the QDMTT jurisdiction could choose to use the GIR or rely on the information included in the GIR and QDMTT Safe Harbour jurisdictions should require the same information of the GIR in the same format. Deadline for filing of the GIR and the notification

7. The filing deadline for the GIR and the notifications as agreed by the IF and stipulated in the GloBE Rules is no later than 15 months after the last day of the Reporting Fiscal Year (extended to 18 months for the transitional year). This approach ensures that MNE Groups have sufficient time to compile, verify, and reconcile the data necessary to prepare and complete the GIR. In contrast, earlier (and inconsistent) timelines are likely to leave in-scope MNE Groups with insufficient time to properly file the GIR in some cases, thereby increasing compliance costs (e.g. MNEs need to track different timelines across different jurisdictions) and risk of errors or inconsistencies in the data reported through the GIR.

8. In most cases, jurisdictions have also aligned the notification deadline with that of the GIR filing. This alignment allows in-scope MNE Groups to determine, at the time the GIR is filed, whether the jurisdiction where the GIR is filed will be able to exchange it with the local jurisdiction. Otherwise, there is a risk that information included in the notification may become incomplete or inaccurate if relevant circumstances change by the time the GIR is filed (for example, a change in the UPE, or the activation of an exchange relationship under the MCAA).³⁹

9. More generally, ensuring that in-scope MNE Groups have a reasonable and consistent period to prepare and file both the GIR and the notification across jurisdictions is commonly viewed as an effective way to simplify and enhance compliance with the GMT framework. Single filer

10. Most jurisdictions allow a single group entity - whether a local Constituent Entity or a foreign UPE - to file the Notification on behalf of all local Constituent Entities, consistent with the single-filer approach. 39 One jurisdiction requires the Notification to be filed earlier. In this case, the Notification serves a dual purpose: it informs the tax administration that the GIR will be received through AEOI, and in addition is used to assist with the identification of the in-scope MNE population ahead of the first GIR filings, performing a role similar to an initial registration step).

Best practices for GIR and Notification

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes guidelines for the following best practices for filing and notification of the GIR: • Enable central filing in XML format. Allow the GIR to be filed in another jurisdiction where the conditions of Article 8 of the GloBE rules are met (i.e. central filing). Where central filing is not yet possible for practical reasons, take the necessary steps to allow central filing as soon as possible (e.g. signature of the MCAA, and activation of exchange relationships). Allow filing of the GIR in XML format, consistent with the GIR XML schema. • One-time notification based on the GIR template. Align the notification return with the standardised template developed in Annex B to the standardised GIR template. Require notification only one-time, with an obligation for the company to report any subsequent changes or updates. If annual notifications cannot be avoided, allow companies to simply confirm (“tick a box”) when nothing has changed since the prior year. • Align the deadline for the GIR and the notification. Align the deadline for filing the notification with the GIR, so MNE Groups have the information necessary to assess where they will file the GIR.

4.1.4. GMT return

1. While the GIR contains all information necessary to compute and determine the jurisdictional top-up tax liability, a domestic GMT return is generally required to give legal effect to that top-up tax liability and to trigger the payment obligation. The obligation to prepare a GIR is separate from the requirement to declare and pay taxes under a tax return. The operation of tax return filing and payment obligation rules is left to the determination of each implementing jurisdiction and is generally expected to be in line with those currently required under that jurisdiction’s existing tax filing and payment procedures. This means that jurisdictions may, in some cases, require additional data points to be reported beyond the GIR for purposes of the preparation of the tax return (for instance, to convert the Top-up Tax liability into the domestic currency).

2. Implementing jurisdictions have taken different approaches with respect to the GMT return. The majority of jurisdictions have introduced a specific GMT return. Among these jurisdictions, some jurisdictions provide for two returns (e.g. one for QDMTT and a combined IIR/UTPR return) and a minority of jurisdictions use three returns (one separate return for each charging provision).

3. A few jurisdictions have integrated the GMT return into their domestic CIT return. While this might seem as a simplification and reduction of the administrative burden on the MNE Group, it is noted that where the CIT return is due only a few months after the end of the fiscal year, providing the GMT information in advance of filing the GIR actually requires the MNE Group to perform early calculations for that particular jurisdictions, could raise risks of errors and thus increase the burden on the MNE Group as further discussed below. Information required

4. As noted in Commentary to the GIR⁴⁰ implementing jurisdictions are generally expected to refrain from requiring the reporting of additional data points in the tax return that go beyond the GIR. Where such 40 OECD (2025), Tax Challenges Arising from the Digitalisation of the Economy – GloBE Information Return (January 2025), paragraph 3. additional information is required implementing jurisdictions are encouraged to adopt a minimalist approach and request only the information necessary to compute the local liability that is not already included in the GIR. In practice, this is generally limited to: • the currency conversion rates applied to translate GIR amounts into local currency; and • the amount of tax due under each applicable charging rule (QDMTT, IIR, UTPR), including an entity-level breakdown where relevant.

5. Some jurisdictions have introduced tax return requirements that duplicate items already reported in the GIR, such as GloBE income, Covered Taxes, components of the Substance-based Income Exclusion, Safe Harbour applications, GloBE elections, local Constituent Entities, etc. As this information is already contained in the GIR and accessible to tax administrations, duplication could provide limited additional value while increasing compliance burdens. Some in-scope MNE Groups reported that additional items reported in the local tax returns need to be verified and validated by their local teams, creating an additional and burdensome verification process within the group that would otherwise not be necessary (as a central team within the group is generally responsible for preparing and filing the GIR). A consistent view also emerged from the discussion within the Amsterdam Dialogue that information already reported in the GIR is not required again in domestic GMT return(s) and that any additional information required relates, for instance, to liability, timing and method of payment or identification of the taxpayer and contact details, rather than the determination of a Constituent Entity’s top-up tax. Deadline for filing the GMT return

6. A clear point of convergence among implementing jurisdictions is the alignment of the GMT tax return deadline with the GIR filing or receipt deadline. In almost all cases the filing date for the GMT return is the same or later than the GIR deadline (i.e. 15 months after the end of the Reporting Fiscal Year). Jurisdictions adopting this approach generally consider that requiring the tax return before the GIR deadline would create practical and legal challenges with limited or no administrative benefit. First, it would oblige MNE Groups to undertake complex GloBE calculations before finalising the GIR, without the benefit of the extensive reconciliation and verification work associated with the preparation of the GIR. This increases compliance costs, the likelihood of inaccuracies or inconsistencies, and the need for later amendments. In particular, the computations depend on the financial numbers that might not only change during and shortly after the Financial Year, but also under the GloBE Rules require allocation among different jurisdictions. As such, determining the GloBE Income or Loss, Covered Taxes and factors embedded in the Substance-based income Exclusion is only possible once the MNE Group performs the calculations for the entire group in all jurisdictions in which it operates, and files the GIR.

7. Second, the deadline for filing the GMT return will generally have implications for the statute of limitation. Statutes of limitation applicable for the CIT on average range between 4 to 6 years, usually starting by the filling of the tax return and may be suspended or extended in certain circumstances (e.g. where an audit is initiated, information requests remain outstanding, or other procedural rules apply). As such, under the CIT the period provided is relatively long. Such a long period is considered necessary to provide the tax administration with sufficient time to review the different data points underlying CIT calculations, including reviewing any cross-border payments and complex documentation on transfer pricing, any potential restructuring transactions impacting the income and assets, as well as any other specifications including tax consolidation.

8. An important difference between the CIT and GMT is that a CIT return is usually filed relatively shortly after the end of the fiscal year (on average within 3-6 months), while the GIR and any GMT returns are due no later than 15 months after the end of the financial year. Tax administrations cannot meaningfully verify the GMT return until the GIR has been filed or exchanged, rendering the period between an early return and the ultimate receipt of the GIR largely unproductive. Since it is advisable that the deadline for the GMT return filing is aligned with the GIR filing deadline, the statute of limitations might require adjustments.

9. This could be achieved in two ways. First, since all the relevant information will be provided to the tax administration only once the GIR is received, the statute of limitation for the purposes of the GMT should only start running once the information from the GIR is received by a given jurisdiction. Alternatively, the statute of limitation could be adapted so that its period of duration is prolonged at least for the same length as the period between the end of the fiscal year and the filling of the GIR, i.e. 15 months.

10. The majority of the jurisdictions that have already legislated the GMT have also extended the duration of their statute of limitation to 5-7 years. In case of fraud, the statute of limitation is usually longer, i.e. 10 years, in some jurisdictions even 20 years.

11. It is recognised that there might be rare situations where some jurisdictions have domestic limitations and are not in a position to adjust their statute of limitations. In those cases, it might be justifiable to require the GMT return earlier, but it is advisable to retain the information required to the simplified set of data points.

12. A small number of QDMTT-only jurisdictions reported exploring the possibility of embedding the QDMTT return into their existing CIT return, especially in cases where the GIR is filed locally (i.e. pending finalisation of their AEOI framework). While it may appear administratively convenient to rely on existing procedures, using CIT returns generally leads to requiring filing within 3 to 6 months after fiscal year-end, which is well before the GIR is filed or exchanged. Advancing the GMT return deadline to match the CIT timeline would avoid this mismatch in the relevant jurisdiction but introduce the other challenges discussed above, including premature GloBE calculations and higher risk of errors and inconsistencies. As a result, aligning GMT return timelines with the GIR deadline is advisable, including for QDMTT-only jurisdictions. Single filer

13. Given that the GMT relies heavily on group information for calculating top-up taxes, compliance processes have proven more efficient when streamlined through a single point of contact within the MNE Group. In practice, most implementing jurisdictions have adopted a single-entity filing, under which one designated entity within the MNE Group – typically the UPE or another nominated local constituent entity – completes all local filing GMT obligations (including QDMTT, IIR, and UTPR) on behalf of all group entities located in the jurisdiction.

14. This approach reduces duplication, lowers compliance costs, and improves the quality of the information reported, as the designated filer usually has access to the group information needed for a correct application of the rules (e.g. consolidated financial data, identification of the UPE or DFE). It is also more consistent with the fact that most in-scope MNE Groups report managing their GMT compliance across jurisdictions from a central team within the group (typically in the parent entity or a regional hub), with the role of local teams being typically limited to verifying the information provided by that central team.

15. Where possible, implementing jurisdictions have enabled single filer approach to cover all domestic compliance obligations including filing and follow-up requests. Some jurisdictions have also allowed the designated filer to be a foreign group entity, where domestic law does not prevent cross-border filings. Some jurisdictions still permit the foreign filer to meet the local filing obligations, while the domestic payment is required to be executed by a local affiliate.

16. To avoid unnecessary administrative burden, jurisdictions adopting the single filer approach have generally chosen not to require upfront documentation demonstrating that the filing entity has authorisation from other group members. Instead, such evidence is typically requested only upon inquiry or audit. Experience suggests that requiring this documentation at the registration or notification stage would add complexity without improving compliance outcomes.

Best practices for GMT return

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit sets out the following guidelines for best practices for the GMT return: • Avoid requesting duplicative and additional information. In the GMT return do not require duplicative or additional information as compared to the information required under the GIR, if not necessary. For GMT returns, the only key items are generally: o Currency conversion rates used,

o Amount of tax due under each of QDMTT, IIR, UTPR (by entity, if relevant). • Align the deadline with the GMT timeline. The deadline for filing the GMT return should be aligned with the GIR filing date to minimise administrative burden both on tax administrations and MNE Groups. Ensure that effective period of the statute of limitation is sufficiently long to allow for a proper risk assessment of the GMT liability. This could include either extending the statute of limitation and/or ensuring it starts running only once the GIR information is received. • Single filer. Allow one Constituent Entity to act as the single filer and point of contact for all the group’s compliance needs in that jurisdiction under the GMT (i.e. DMTT, IIR, and UTPR obligations). Where possible, a Constituent Entity should not be required to prove it has permission from other group entities, as such evidence can be required through a follow-up request if necessary. Where possible, allow a foreign group entity to take this role in the jurisdiction.

4.1.5. Top-up tax Payment

Deadline for payment

1. Approaches to GMT payment deadlines are typically linked to choices with respect to the deadline for the GMT return. In jurisdictions where the GMT return deadline is aligned with the GIR, the due date for payment is usually set on the GMT return deadline or shortly thereafter. This alignment is considered particularly important where statutes of limitation begin when GMT return is filed, ensuring tax administrations have sufficient time after receiving also the GIR to conduct reviews, request additional information, or initiate risk assessments and audits. By contrast, jurisdictions that integrated the GMT information in the CIT return in such a way tie the GMT payment deadline to CIT timelines, could create the issues identified above (see Section 4.1.4.).

2. Another design consideration for jurisdictions is whether to introduce advance payments or instalments similar to those used in some CIT systems. The overwhelming majority of jurisdictions have not adopted such systems and view them as inconsistent with the objectives and design of the GloBE Rules and particularly burdensome both on the tax administrations and the MNE Groups. Requiring an upfront payment would impose an obligation on the MNE Group to compute the top-up tax liability (and thus undertake all relevant calculations) for those jurisdictions months in advance of calculating the top-up tax liability for all other jurisdictions. Since the underlying figures required for the calculation of the top-up tax depend also on allocation of tax attributes among different jurisdictions, advance calculations for only one jurisdiction might not produce precise results. For these reasons, advance payment regimes are generally not advisable. Single payor

3. In relation to payment, many jurisdictions extend the single-filer concept by allowing an MNE Group to appoint one local Constituent Entity to pay the GMT liabilities on behalf of all local entities of the group. For this system to function effectively, jurisdictions typically provide for joint and several liability among all local Constituent Entities covered by the election, ensuring that unpaid amounts can be recovered from any local group entity.

4. Single filer and payor approach allows the tax administrations to manage communication and administration related to the payment with one entity and in such way streamline and ease the administrative burden on both the tax administration and the MNE Group while enforcing liabilities across several entities and thus minimising the recovery risk if the designated filer or payor fails.

Best practices for Top-up Tax payment

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes the following guidelines for best practices for top-up tax payment: • Avoid requiring advance or instalment payments. Align tax payment due dates with the GIR and tax return filing dates, or shortly after. • Single payor. Ensure the option to appoint a single payor for the in-scope MNE is operational by providing joint and several liability mechanisms among all local Constituent Entities of the MNE.

4.1.6. Penalties related to upfront compliance

1. Besides requiring that the laws of each jurisdiction with respect to penalties, and sanctions, also apply to the GIR,⁴¹ the GloBE Model Rules do not impose any specific requirements with respect to penalties. Jurisdictions may extend existing penalties or sanctions (as well as any penalty or sanction mitigation provisions) or to create new ones for the GIR. New penalties and sanctions in respect of the GIR should be commensurate with penalties or sanctions in respect of other information returns and other information return filing obligations in the jurisdiction.

2. The implementing jurisdictions have aligned penalties with domestic considerations and a wider compliance culture. At the same time there is a common understanding amongst the members of the Inclusive Framework on transitional penalty relief that is designed to encourage implementing jurisdictions to provide a measure of relief for MNE Groups in the initial years during which the GloBE Rules come into effect.⁴² A discussion of the common understanding on transitional penalty relief is discussed further later in this section.

3. The majority of jurisdictions have provided for distinct penalties for the GMT, separating them from the generally applicable penalties under their domestic CIT obligations. The penalties apply equally for 41 OECD (2021), Tax Challenges Arising from the Digitalisation of the Economy – Global Anti-Base Erosion Model Rules (Pillar Two): Inclusive Framework on BEPS, OECD Publishing, Paris, https://doi.org/10.1787/782bac33-en, Article 8.1.8. 42 See below in this section and OECD (2022), Safe Harbours and Penalty Relief: Global Anti-Base Erosion Rules (Pillar Two), OECD/G20 Inclusive Framework on BEPS, OECD, Paris. https://www.oecd.org/content/dam/oecd/en/topics/policy-sub-issues/global-minimum-tax/safe-harbours-and-penaltyrelief-global-anti-base-erosion-rules-pillar-two.pdf, Chapter 3. local compliance requirements such as registration and filing of the GMT return, as well as for the filing of the GIR. The following sections outline important considerations and best practices in ensuring an effective yet proportionate penalty system. Design of penalties

4. In designing the penalties, jurisdictions should consider different aspects of the framework including the (i) amount of penalties and (ii) different type of non-compliance that triggers the penalty obligation.

Amount of penalties

1. The amount of penalties should be set at a level that is effective so to incentivise compliance. Penalties in relation to compliance with the GMT should be appropriate, dissuasive and effective, yet proportional. In addition, the jurisdictions could consider introducing a cap for a given fiscal year to avoid excessive amounts of penalties on the in-scope MNE.

2. There are different approaches to the design of the rules on penalties and ensuring their effectiveness and proportionality. For instance, the amount of the penalties can be fixed or it can be progressive, with the amount increasing as a proportion to the non-compliance. For example, some jurisdictions have introduced a penalty that increases depending on the time ranges of the delay in registration or filing of the GMT return or the GIR. Other jurisdictions have a daily rate applied based on the non-compliance item and the length of the delay. Both approaches lead to a higher penalty where the duration of the non-compliance is longer.

Type of non-compliance

1. Jurisdictions already provide for penalties with respect to compliance obligations within their general CIT framework. This general CIT framework usually distinguishes between different compliance obligations and consequently attaches different penalties. As such many jurisdictions provide for penalties linked to a different type of non-compliance distinguishing between failure to meet filing obligations, and cases where an MNE Group files the GMT return or the GIR but in that return provides incomplete or incorrect information. A separate treatment is applied to cases where the information provided is incorrect because the taxpayer acted with fraudulent intent or in gross negligence.

Failure to meet filing obligations

1. Almost all implementing jurisdictions have extended the application of the existing penalty framework or have introduced specific GMT penalties related to the registration (where applicable), and filing of the GMT return.

2. With respect to the filing of the GIR and the related Notification, jurisdictions have provided for a distinct penalty, since such an obligation cannot be linked to any other general filing obligation. The penalty framework should avoid imposing the penalties where the information filed in the GIR was not received by the receiving jurisdiction due to the fault of either the sending or the receiving jurisdiction, and not the MNE Group. Similarly, the penalty framework should also avoid imposing the penalties where failure to meet filing obligations was a result of a lack of readiness or an error in the user portal on the side of the tax administration.

Incomplete or incorrect information provided

1. On some occasions, the in-scope MNE Group could register, file or notify on time and in good faith, but the information provided in the registration form, the GMT return or the GIR is either incomplete or incorrect. For such cases, the jurisdictions could introduce penalties that either cover both situation or provide different penalties for a case where the information is incomplete, or information is incorrect. Some jurisdictions have introduced penalties per data point. However, considering that the GIR has about 480 data points, such an approach could lead to disproportionately high penalties and is thus not advisable. Instead, an absolute amount that is imposed on the basis of the information return as a whole being incomplete or incorrect is a more proportionate approach.

2. Many implementing jurisdictions allow the in-scope MNE Group additional time to provide the missing information or correct the incorrect information. Once the MNE Group complies and either supplements or corrects the information, the penalty is usually reduced or waived. Providing such a “grace period” when an MNE Group acts in good faith is considered advisable. This approach minimises additional costs on the MNE Groups and at the same time incentivises compliance, even after an initial deadline was not met.

Fraudulent information provided

1. Information provided in the GMT return or the GIR could in some instances be incorrect due to fraudulent intent or gross negligence on the side of the MNE Group, leading to a lower or even no top-up tax liability assessed by the in- scope MNE Group. For such cases, jurisdictions could provide for specific penalties taking into account the seriousness of the offense. Providing for appropriate yet proportional penalties for these cases would dissuade the in-scope MNE Groups from such behaviour.

2. Cases where information provided is incorrect due to intent or gross negligence are usually considered tax fraud or evasion in many jurisdictions. The notions and concepts as they currently stand under the laws of most jurisdictions should capture any tax evasion or fraud that relates to the GMT. Therefore, it is not necessary to recharacterise the definition of a tax fraud or evasion for GMT purposes.

Late payment

1. An MNE Group might have complied with all the filing and notification requirements and has selfassessed that a top-up tax is due. On the basis of the self-assessed top-up tax in the return, the MNE Group and/or its Constituent Entities located in that jurisdiction are liable to pay the top-up tax within the prescribed deadline. Where the payment is late, many jurisdictions impose a penalty for this non-compliance. The penalty could be designed as a fixed amount or an amount determined as a percentage of the top-up tax ultimately due. Some jurisdictions have also prescribed the amount of the penalty for the late payment by referencing it to the duration of the delay. Under this approach, the total amount increases as the delay in payment gets longer. In addition, jurisdictions could impose interest in case of a late payment that is usually prescribed as a percentage to the top-up tax due. The penalty framework should also avoid imposing the penalties where failure to meet or payment obligations was a result of a lack of readiness or an error in the user portal on the side of the tax administration.

Box 27. Overview of penalties across implementing jurisdictions

In the context of the Amsterdam Dialogue, some implementing jurisdictions shared information on their penalties frameworks. The below overview serves as a set of examples, rather than as set of best practices.

In relation to registration obligations, jurisdictions take different approaches. Some, such as New Zealand, provide for a specific monetary cap (NZD 100 000 (approx. EUR 56 000)). Others, such as Canada, do not impose a stand-alone penalty for failure to register; however, registration is a precondition for filing the GIR and paying liabilities, so enforcement operates indirectly through filingrelated penalties.

Jurisdictions have established penalties for late or non-submission of domestic GMT returns. Spain applies surcharges of 1% to 15% for late filing and penalties of 50% to 150% of unpaid tax in more serious cases. In Poland, provisions of the Fiscal Penal Code apply, with fines of up to 720 daily rates (each approximately EUR 33.71 to EUR 13 484). Australia imposes a late filing surcharge of up to 10% of the self-assessed tax if the delay is not excusable, with surcharges below EUR 50 not charged. The United Kingdom has followed the same approach as for CIT and as such applies a progressive regime from £100 (approx. EUR 117) up to the higher of £200 (approx. EUR 234) or 20% of unpaid tax.

Penalties for late or non-filing of the GIR tend to be higher. The Netherlands may apply penalties up to EUR 1,030,000 depending on the severity of the non-compliance. Canada may apply CAD 25 000 per month (approx. EUR 17 000), up to CAD 1 000 000 (approx. EUR 680 000), combining escalation with a cap. Canada has implemented the transitional penalty relief in accordance with Annex C of the GIR. Kenya applies 5% of the tax due or KES 10 000 (approx. EUR 65), whichever is higher. Austria fines up to EUR 100 000 in cases of intent and up to EUR 50 000 in cases of gross negligence. Germany caps penalties at EUR 30 000, whereas Spain and Portugal combine fixed base amounts (e.g. EUR 10 000 per data item in Spain, capped at 1% of group turnover; EUR 5 000 to EUR 100 000 in Portugal) with turnover-based limits or daily increases.

Transitional penalty relief

1. The common understanding on transitional penalty relief is intended to allow time to familiarise themselves with the rules and develop the data collection and the reporting and compliance systems without the risk of being penalised for making reasonable mistakes. The common understanding applies for the 2026 and 2027 in which filing for 2024 and 2025 fiscal years will take place and provides that during the transition period,⁴³ no penalties or sanctions should apply in connection with the filing of a GIR where a tax administration considers that an MNE has taken “reasonable measures” to ensure the correct application of the GloBE Rules.

2. A majority of jurisdictions provide for penalty relief where the non-compliance can be attributed to justifiable reasons. Some have explicitly implemented the Administrative Guidance into their domestic law, some did not consider it necessary to implement it separately as they already provide for such a relief under the general provisions of their domestic tax law. At the same time, a few jurisdictions do not provide the penalty relief, due to implications under their domestic policy. In particular, one jurisdiction has noted that it can be difficult to define and apply an open-ended standard such as “reasonable measures” or “justifiable reasons” with sufficient legal certainty and predictability. 43 The transition period for the purposes of the transitional penalty covers fiscal years ending before 30 July 2028.

3. As agreed in the transitional penalty relief, an MNE Group can demonstrate it has taken reasonable measures if it can demonstrate it has, in good faith, put in place the appropriate systems to understand and comply with the rule. Whether a taxpayer has met the standard of taking reasonable measures must be assessed by a tax administration based on the facts and circumstances of the case. It is recognised that determining whether an MNE Group has taken “reasonable measures” is a fact and resource intensive exercise. Instead, jurisdictions could consider extending filing deadlines and allow additional time for correcting the returns in this transitional period (i.e. provide for a grace period). Liability for penalties and interests

4. Similar as for liability to the top-up tax, the jurisdictions can consider imposing the liability for penalties and interest on the local constituent entity. Imposing penalties on the local constituent entity prevents the penalties from being imposed on an extraterritorial basis (as would be the case if the penalties were instead imposed on for instance, a UPE in another jurisdiction). From a practical perspective, penalties also are more easily collected from the local constituent entity.

5. In addition, jurisdictions can consider to prescribe a joint and several liability among local constituent entities also for penalties and interests.

Best practices for Penalties for upfront compliance

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes the following guidelines for best practices in respect of penalties for upfront compliance: • Provide for appropriate GMT penalties. Ensure the penalties for GMT compliance are appropriate, taking into account that GMT applies only to large MNE Groups. • Provide for dissuasive, effective GMT and proportional penalties. Design the amount of the penalty either in an absolute or relative amount, but with a potential progressive scale and a cap to limit overall penalty liability per financial year. For late payments of the top-up tax due, consider providing for a penalty in a relative amount together with an interest. • Allow for a grace period. In case of incomplete or incorrect information provided, enable time for the in-scope MNE Group to first supplement or correct the information before imposing a penalty. • Give transitional period relief. Provide a penalty relief in the transition period where the MNE has taken reasonable measures in applying the GloBE Rules or extend local filing deadlines.

Module 5. Exchange of Information

Introduction

1. This Module focuses on the role of central filing and automatic exchange of the GIR in the effective administration of the GloBE Rules. It outlines the legal and operational framework and conditions required to enable jurisdictions to rely on central filing arrangements and to exchange GIR information in a timely, secure and consistent manner. By setting out key legal and operational considerations for implementing the GIR exchange framework, this module provides guidance to tax administrations on establishing efficient processes that minimise administrative and compliance burdens and support a consistent implementation and application of the international exchange framework under the Multilateral Competent Authority Agreement on the Exchange of GloBE Information (GIR MCAA).

2. As described further in Module 4, the GIR is a standardised information return that has been developed by the IF to support the administration and application of the GloBE Rules by tax administrations. It provides the information necessary to enable implementing jurisdictions to perform an appropriate risk assessment, identify Safe Harbour elections and verify the calculation of an MNE Group’s liability under the GloBE Rules and, where applicable, a Qualified Domestic Minimum Top-up Tax (QDMTT). The GIR reflects an agreement among IF members on a complete and standardised set of data points that are expected to be needed in order to understand the top-up tax calculation and undertake an appropriate risk assessment. In addition to defining the information to be collected, the GIR incorporates a dissemination framework designed to ensure that each jurisdiction receives only the information that is relevant for the determination of any top-up tax liability arising in that jurisdiction, taking into account the application of the GloBE rules in other jurisdictions and the allocation of taxing rights across the system.

3. The GIR consists of two parts: (i) the General Section contains general information relating to the MNE Group as a whole, including information on the group structure and an overview of the application of the GloBE Rules at group level; (ii) the Jurisdictional Sections contain jurisdiction-specific information reflecting the detailed application of the GloBE Rules and, where applicable, the QDMTT, in respect of each jurisdiction in which the MNE Group has Constituent Entities.

4. To support the practical implementation of the GIR, the I F has further developed a standardised XML schema that renders the GIR in a machine-readable format. This common schema, described in further detail below at Section 5.2.1, is intended to facilitate consistent electronic filing by MNE Groups and enable tax administrations to efficiently process, validate, and exchange the relevant information in accordance with the agreed dissemination framework.

5. In terms of filing obligations, Article 8.1.1 of the GloBE Model Rules requires each Constituent Entity of an MNE Group to annually file a GIR (in the form of the XML schema) with the tax administration of the jurisdiction where it is located, in order to support the administration of the GloBE Rules (i.e., local filing). However, Article 8.1.2 of the GloBE Model Rules provides that a Constituent Entity is discharged from the local filing where a GIR conforming to the same requirements is filed by the filing deadline by the U PE or a Designated Filing Entity located in a jurisdiction that has a Qualifying Competent Authority Agreement in effect with the jurisdiction of the Constituent Entity (i.e., central filing).

6. To give effect to the central filing mechanism provided for under the GloBE Model Rules, a framework for the exchange of information in respect of the GIR has been developed under international agreements. The central filing, together with the exchange of information framework, reduces the number of local filings, by enabling tax administrations to rely on information exchanged between Competent Authorities for the administration of the GloBE Rules and, where applicable, a QDMTT. The use of a harmonised XML format also supports secure and timely information exchange between jurisdictions, ensuring that each tax administration receives the data necessary for the determination of any top-up tax liability within its jurisdiction.

5.1. Legal implementation of the exchange of information under the GloBE Rules

1. The following sections describe the legal instruments that support the exchange of GIR information and explain how these instruments interact with the filing rules under Article 8 of the GloBE Rules to give effect to the central filing mechanism, including through the operation of the Dissemination Approach, which determines the scope of information to be exchanged with each jurisdiction. 5.1.1. Description of the international exchange framework

2. Where central filing is relied upon, the operation of Article 8.1.2 – as an exception to the default local filing mechanism – depends on the ability of Competent Authorities to exchange annually the relevant GIR information on an automatic basis. As such, the administration of the GloBE Rules is based on GIR information exchanged by Competent Authorities rather than information obtained directly through local filing.

3. The legal basis for this exchange is the Convention on Mutual Administrative Assistance in Tax Matters (MAAC),⁴⁴ which authorises the automatic exchange of information that is foreseeably relevant for the administration of their tax laws and allows Competent Authorities to mutually agree on the scope and modalities of such exchanges. All GIR information exchanged remains subject to the confidentiality rules and other safeguards provided for in the MAAC, including the provisions limiting the use of the information exchanged.

4. On this basis, the GIR MCAA⁴⁵ has been developed and agreed by the IF. It constitutes a Qualifying Competent Authority Agreement for purposes of the GloBE Rules. Under the GIR MCAA, Competent Authorities exchange GIR information on a bilateral basis when an exchange relationship is active, following the completion of the notification process provided for under Section 8 of the Agreement. Through the notification process, Competent Authorities confirm that they are legally and operationally in a position to send and/or receive GIR information and indicate with which exchange partners they wish to establish relationships for sending and/or receiving GIR information. The GIR MCAA is designed to facilitate the automatic exchange of GIR information to the widest extent possible, including on a nonreciprocal basis where a Competent Authority indicates its willingness to send information without receiving information in return, or to receive without sending GIR information.

5. As further specified in paragraph 9 of the Commentary to the GIR MCAA, the language of the MCAA does not explicitly require jurisdictions to have implemented the GMT in order to collect the GIR and to activate an exchange relationship with other jurisdictions pursuant to Section 8. However, the GIR MCAA does require all jurisdictions to have an adequate legal and operational framework in place to allow for filing and exchange of GI Rs. The existence of and compliance with the framework will be the object of 44 OECD and Council of Europe (2011), The Multilateral Convention on Mutual Administrative Assistance in Tax Matters: Amended by the 2010 Protocol, OECD Publishing. http://dx.doi.org/10.1787/9789264115606-en. 45 OECD (2025), Tax Challenges Arising from the Digitalisation of the Economy – Multilateral Competent Authority Agreement on the Exchange of GloBE Information (January 2025), OECD/G20 Inclusive Framework on BEPS, OECD, Paris, https://www.oecd.org/content/dam/oecd/en/topics/policy-sub-issues/global-minimum-tax/multilateralcompetent-authority-agreement-exchange-of-globe-information.pdf. a peer review, as approved by the IF. Jurisdictions may participate in the exchange framework under the GIR MCAA pending the outcome of the peer review.

6. The GIR MCAA establishes the scope and modalities for the automatic exchange of GIR information, including the conditions under which such exchanges are to take place between Competent Authorities. In particular, it defines the categories and scope of information subject to exchange in accordance with the Dissemination Approach;⁴⁶ the timing, format and manner in which information is to be exchanged;⁴⁷ and the procedural rules governing the activation, deactivation and termination of exchange relationships through notifications to the Co-ordinating Body Secretariat.

7. The GIR MCAA further sets out the obligations of Competent Authorities with respect to confidentiality, data safeguards and the proper use of exchanged information, building on the legal protections provided under the MAAC.⁴⁸ Jurisdictions that wish to receive information under the GIR MCAA are required to fill a notification confirming that they have passed the Global Forum assessment⁴⁹ and therefore can notify that their jurisdiction has in place adequate measures to ensure the required confidentiality and data safeguards standards.

8. Taken together, these elements are intended to ensure that the exchange of GIR information operates in a coordinated, secure and effective manner and supports the consistent and efficient implementation of the GloBE Rules.

9. In addition to the MAAC and the GIR MCAA, jurisdictions may rely on other international legal instruments that permit the automatic exchange of information and qualify for purposes of the GloBE Rules, such as Double Tax Conventions and Tax Information Exchange Agreements. For example, between Member States of the European Union, the exchange of GIR information is supported by the legal framework on administrative cooperation in the field of taxation, as amended by Council Directive (EU) 2025/872 (DAC 9). 5.1.2. Specific aspects for implementation Central filing and Dissemination Approach

10. The central filing and information exchange mechanism foreseen under Article 8.1.2 of the GloBE Model Rules provides that tax administrations will receive the GIR through an exchange of information and that a local filing obligation will generally only apply where the return has not otherwise been filed in a jurisdiction that has entered into a Qualifying Competent Authority Agreement with that jurisdiction.

11. From the perspective of jurisdictions that have implemented an IIR or UTPR, an active exchange relationship with the Competent Authority of the UPE or DFE jurisdiction has the effect of switching off local filing obligations, where the GIR has been centrally filed, thereby avoiding duplicative reporting and ensuring that the GIR is collected and disseminated through the international exchange framework. This exchange mechanism provides clear advantages over local filing, allowing the MNE to limit its filing obligations to a single jurisdiction and allowing the tax administration in that jurisdiction to act as the primary point of contact for the filing, validation and any subsequent amendments or corrections. This approach enhances data consistency, facilitates a more efficient and coordinate handling of corrections, and 46 Section 1(1)(f) of the GIR MCAA. 47 Sections 2 and 3 of the GIR MCAA. 48 Section 5 of the GIR MCAA. 49 Global Forum on Transparency and Exchange of Information for Tax Purposes’ mechanism to assess Confidentiality and Data Safeguards for AEOI (CTPA/GFTEI(2020)3). strengthens confidentiality and data protection of information since the information originates from a single source rather than from multiple parallel filings across Implementing Jurisdictions.

12. The same considerations apply to QDMTT-only Jurisdictions. While there is no requirement in the Model Rules for QDMTT jurisdictions to use the same format as the GIR for information collection purposes, QDMTT jurisdictions which are eligible for the QDMTT Safe Harbour must ensure that the computations required under that QDMTT only rely on the equivalent data points that the MNE would otherwise have used to compute its GloBE tax liability under the GloBE Model Rules.⁵⁰ This requirement extends to the use of the XML format set out in the Schema. As the GloBE Model Rules ensure that the data points required for the computation of the QDMTT are functionally equivalent to those required to compute the GloBE tax liability, the use of the GIR and central filing is, in principle, also recommended for QDMTT- only Jurisdictions, except in cases where the jurisdiction does not qualify for the QDMTT Safe Harbour.⁵¹

13. A central and a distinct feature of the legal framework for the exchange of GIR information is the Dissemination Approach. The Dissemination Approach – discussed below under Section 7.2.3 – determines in which circumstances and to which extent a General Section or one or more Jurisdictional Sections of the GIR are relevant for a jurisdiction and therefore should be exchanged with such jurisdiction, having regard to the allocation of taxing rights under the GloBE Rules. Timing and frequency of the exchanges

14. The timing of the filing and exchange of the GloBE Information Return is governed by Article 8.1 of the GloBE Model Rules, which requires filing within 15 months of the end of the Reporting Fiscal Year (18 months in the transition year) and provides for the exchange of the GIR between Implementing Jurisdictions. In order for the exchange framework to operate efficiently, Section 3 of the GIR MCAA foresees that information is generally to be exchanged within three months following the filing deadline.

15. Section 2 of the GIR MCAA provides the legal basis for the exchange and sets out the information that will be exchanged. In general, exchanges in respect of a specific group will take place on an annual basis. However, information may also be exchanged more frequently than once a year, where appropriate. This may be necessary, for example, when a Competent Authority receives corrected GIR information which would then be sent to the other Competent Authority as soon as possible after it has been received.

16. More frequent exchanges will also be required where MNE Groups have different Reporting Fiscal Year ends, resulting in staggered filing deadlines and requiring jurisdictions to conduct multiple exchanges in order to receive all relevant GIRs within the applicable timeframes and exchange them with partner jurisdictions. More frequent exchanges may also be due where a GIR is re-submitted following a rejection upon the first filing, giving rise to a new exchange of GIR information.

17. In any case, as a matter of best practice to promote administrative efficiency, the frequency of GIR exchanges is encouraged to be on a regular basis (e.g. no less frequent than every two or three months, subject to domestic operational capacities). Collaboration on corrections, compliance and enforcement

18. The GIR MCAA further establishes a framework for cooperation between Competent Authorities in relation to corrections, compliance and enforcement, including procedures for notification, consultation and the exchange of corrected information where information previously exchanged is incomplete or 50 See Chapter 3 of Appendix A, paragraph 51, of the Consolidated Commentary to the GloBE Model Rules (2025). 51 See Chapter 10, paragraph 118.42, of the Consolidated Commentary to the GloBE Model Rules (2025). inaccurate or where the information was not exchanged by the deadline stipulated in Section 3 of the GIR MCAA.

19. Particularly, under Section 4 of the GIR MCAA, a Competent Authority may notify another Competent Authority where it has reason to believe that information included in a GIR requires correction or where information subject to exchange has not been exchanged within the applicable timelines. Where corrections are required, the Competent Authority of the jurisdiction in which the GIR was filed is expected to take appropriate measures to obtain the corrected information and to exchange such information, without undue delay, with all Competent Authorities for which the information is subject to exchange.

20. As indicated in Section 5.2.3 below, jurisdictions are encouraged to share the corrected information as soon as possible with receiving jurisdictions and if feasible within 90 days from the receipt of the correction request.

21. This framework is premised on the operation of central filing, therefore the responsibility for obtaining corrected information and ensuring its dissemination rests with the Competent Authority of the jurisdiction where the UPE or DFE have centrally filed the GIR. Through this mechanism, the GIR MCAA ensures that corrections are addressed in a coordinated manner and that all affected jurisdictions receive consistent and updated information for purposes of administering the GloBE Rules.

22. Moreover, where a Constituent Entity has notified its tax administration that the GIR will be filed centrally by a UPE or DFE in another jurisdiction, but the information is not exchanged by the agreed deadline, the receiving Competent Authority may notify the sending Competent Authority accordingly. The sending Competent Authority must then promptly investigate the reason for the non-exchange (e.g. nonreceipt of the GIR, incorrect designation of intended recipient jurisdictions, or technical issues) and inform the notifying Competent Authority within one month, including of the expected exchange date.

23. In such cases, the guidance set out in paragraph 306 on the timing and frequency of exchanges applies, and the GIR should be exchanged in the next possible batch of exchanges, taking into account domestic operational capacities. Activation of exchange relationships

24. As a first step, jurisdictions are required to sign the GIR MCAA and to implement the necessary domestic legal framework to give effect to the exchange of GIR. To become a signatory of the GIR MCAA, the competent authority of the jurisdiction or its designated representative shall sign the Declaration, which is attached to the GIR MCAA. To initiate the signing of the GIR MCAA, a jurisdiction is invited to contact by email the Coordinating Body Secretariat (cb.mac@oecd.org) which will prepare a package for signature. The jurisdiction would need to provide to the Secretariat the name and title of the signatory of the Declaration and the intended signing date. The GIR MCAA is usually signed remotely in the jurisdiction by the person holding competent authority power, or a delegation of powers. The signed package shall be dispatched to the OECD via diplomatic channels. It is also recommended to send a PDF scan to the Coordinating Body Secretariat. Once the original package is received, the Secretariat will acknowledge receipt through a procès-verbal confirming that the jurisdiction is a signatory to the GIR MCAA.

25. The mere signature of the GIR MCAA and its domestic implementation are not, in themselves, sufficient to enable the exchange of information. These are only established and become fully operational once the procedures set out in Section 8 of the GIR MCAA have been completed through the submission of notifications by the Competent Authorities to the Co-ordinating Body Secretariat.

26. Each Competent Authority is required to notify whether it has the legal and operational framework in place to send and/or receive GIR information. This includes the legal framework to implement the GloBE Rules (i.e. whether it has an IIR, UTPR and/or QDMTT in place), as well as a legal and operational framework to ensure central filing and exchange of GIR information. A Competent Authority is further required to specify whether it intends to send information, receive information, or both, and to identify the jurisdictions with which it wishes to activate exchange relationships.

27. An exchange relationship is activated between two Competent Authorities once both have listed each other in their respective notifications in accordance with the GIR MCAA. Although the Agreement is multilateral in nature, exchanges of information take place on a bilateral basis between Competent Authorities for which an exchange relationship is active. Competent Authorities are required to keep their notifications up to date in order to reflect any changes affecting the scope or status of their exchange relationships. For the second and subsequent information exchange cycles, Competent Authorities are expected to activate relationships as soon as possible in advance of filing deadlines, and should aim to do so three months in advance of the filing deadline wherever possible. For example, to meet a 30 June 2027 filing deadline, activation is encouraged to be completed by 31 March 2027. Role of the Co-ordinating Body Secretariat

28. The Co-ordinating Body Secretariat is responsible for the administration of notifications submitted under the GIR MCAA. In particular, it maintains and makes available a list of jurisdictions that have signed the Agreement⁵² and a record of the active exchange relationships between Competent Authorities pursuant to the notifications received.⁵³

29. The Co-ordinating Body Secretariat also supports the operation of the GIR MCAA by facilitating communication between Competent Authorities, including in relation to notifications, consultations and other matters provided for under the Agreement. In case of questions or clarifications regarding the application of the GIR MCAA, including the activation of exchange relationships or the operation of the exchange framework, the Co-ordinating Body Secretariat may be contacted at CB.MAC@oecd.org. 52hhttps://www.oecd.org/content/dam/oecd/en/topics/policy-issues/tax-transparency-and-international-cooperation/gir-mcaa-signatories.pdf. 53 https://www.oecd.org/en/topics/sub-issues/international-standards-on-tax-transparency/automatic-exchange-ofinformation-exchange-relationships.html.

Best practices on legal implementation for the exchange of GIR information

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes the following guidelines for best practices on the implementation of the GIR information exchange framework: • Implement the legal framework for the exchange of GIR information under the GIR MCAA (or other relevant legal instruments), to enable MNEs to effectively rely on central filing and allow the filing of GIR with a single tax administration. • Provide the legal framework for exchanges of information in accordance with the Dissemination Approach. • To promote administrative efficiency, the frequency of such exchanges is encouraged to be on a regular basis. • Submit the relevant set of notifications to the Coordinating Body Secretariat well in advance of the filing deadline to activate exchange relationships under Section 8 of the GIR MCAA, recognising that exchange relationships under Section 8 of the GIR MCAA become active only once matching notifications are confirmed, and, as a best practice three months in advance of the filing deadline, in order to provide taxpayers with timely clarity on whether central filing can be effectively relied upon.

5.2. Operational implementation of exchange of information of the GIR

1. Recognising the benefits of the consistent implementation of the GIR filing requirements, the Inclusive Framework agreed a standardised GIR template to be relied upon by all Implementing Jurisdictions and QDMTT-only jurisdictions, as well as a coordinated Dissemination Approach for the provision of relevant GIR information to jurisdictions. As part of its work on the facilitation of the implementation of the GloBE Model Rules, and with a view to ensuring a consistent, standardised approach to capturing the GIR information, the IF has developed a schema in extensible mark-up language (XML) and a corresponding user guide. 5.2.1. Ensuring the standardised filing and exchange of GIR information GIR XML Schema

2. The GIR XML Schema (the Schema) is the computer version of the GIR. It translates the paper format of the GIR into extensible mark-up language, ensuring standardisation and facilitating the exchange of such information between implementing jurisdictions. The Schema is designed to be used for the exchange of GIR information between Competent Authorities that have activated exchange relationships under the GIR MCAA, or another Qualifying Competent Authority Agreement.

3. Jurisdictions should also use the Schema domestically for the purpose of gathering the GIR information from their respective Filing Constituent Entities. Using the Schema ensures that Constituent Entities provide all the required data points under the GIR, that the GIR is compatible for exchange in an encrypted and secure manner, and that the information can be properly disseminated to all relevant jurisdictions.

4. The GIR XML Schema contains an XSD file of the Schema (the code version of the Schema, to be integrated to the AEOI portal), as well as a related User Guide which explains the information required to be included in each data element to be reported to facilitate the understanding of the Schema, and ease the filing of the information. Both the Schema and the User Guide are available on the OECD website. Common Transmission System

5. As set out in Section 3(5) of the GIR MCAA, Competent Authorities will transmit the GIR information through the OECD Common Transmission System (CTS) and in compliance with the related encryption and file preparation standards.

6. The CTS is an IT-system developed by the Forum on Tax Administration and operated by the Global Forum that allows tax administrations to exchange information in a highly secure and standardised manner. The security of the CTS is ensured through both the legal and operational framework put in place to deliver the CTS. The CTS provides a secure and encrypted “pipe” through which Competent Authorities can bilaterally and securely exchange tax information with one another and is used for a wide range of exchanges, including for purposes of the Common Reporting Standard and Country-by-Country Reporting. Over 100 jurisdictions now use the CTS.

7. Only the intended recipient can access the files transmitted as they are encrypted by the sending jurisdiction prior to their transmission and can only be decrypted by the receiving tax authority following their receipt. Recognising that jurisdictions will have different systems to receive the data from third parties and to prepare the information for sending, the CTS offers Competent Authorities the ability to access the CTS through a server-to-server link-up (SFTP), a browser-based manner (HTTPS), and through an Application Programming Interface (API), in order to send and receive information. The CTS is not a database for the purpose of storing information. Status Message XML Schema

8. Since the data transmitted via the XML Schema may contain errors, such as those arising from incorrect file preparation (file errors) or incomplete or inaccurate substantive GIR information items (record errors), the OECD has developed a common XML Schema to enable Competent Authorities to report such errors in a structured manner. This GIR Status Message XML Schema allows Competent Authorities that have received GIR information through the XML Schema to report back to the sending Competent Authority, on whether the file contained any file-level or record-level errors. The transmission of the Status Message takes place through the CTS as explained above.

9. The GIR Status Message XML Schema may, in addition to communications between Competent Authorities, also be used by a Competent Authority to provide a status message to its domestic Filing Constituent Entities.

10. The GIR Status Message XML Schema comprises the XSD file of the Schema (the code version), as well as a User Guide to facilitate the understanding of each element contained in the Schema. All documents are available on the OECD website. 5.2.2. Ensuring data quality and consistency Validation rules (file errors, severe record errors and record errors)

11. The GIR XML Schema includes the data points to be filed by Filing Constituent Entities but does not allow to check whether data points are filled consistently with the GloBE Rules and GIR notes. To increase the data quality and consistency of the information, the Status Message User Guide also contains a list of validation rules, which are designed to detect errors in the GIR information or with the XML Schema file. Those validations rules are to be developed and integrated into the IT system of the tax administrations. Jurisdictions then consider the moment in the process in which validations should be run – they should be run both prior and subsequent to exchange of GIR information with foreign tax authorities, but tax administrations are also encouraged to run the validations upon delivery of GIR information. The validation rules to be applied to the GIR information are grouped in three categories depending on their nature and importance: file errors, severe record errors and other record errors.

12. File errors generally entail that the receiving Competent Authority is not in a position to open and use the file. As such, file errors are of a fundamental nature and therefore a GIR Status Message is to be sent to the sending Competent Authority in these instances, with a view to timely receiving a new file (without the file error(s)) with the GIR information contained in the initial erroneous file sent. This approach reflects the requirements set out in Section 4 of the GIR MCAA in relation to the notification and remediation of errors that prevent the exchange relationship from operating efficiently.

13. Severe record errors address fundamental issues of data quality of the GIR information received, making the file not usable for tax administration and compliance verification purposes in practice. In case severe record errors are discovered, the receiving Competent Authority should reject the file and send a GIR Status Message to the sending Competent Authority. The sending Competent Authority should timely send a new file (without the severe record error(s)) with the GIR information contained in the initial file sent. As for file errors, this approach also reflects the requirements set out in Section 4 of the GIR MCAA in relation to the notification and remediation of errors that prevent the exchange relationship from operating efficiently.

14. Other record errors address additional issues of data quality in relation to the GIR information received, but do not as such impede the receiving Competent Authority from opening and using the file. The other record errors contained in the GIR Status Message XML are a best practice recommendation, and unlike file errors or severe record errors, are not required to be notified to the sending Competent Authority. However, in case record errors are communicated to the sending Competent Authority through the GIR Status Message XML Schema, the sending Competent Authority is responsible for undertaking best efforts to address these errors and to provide the receiving Competent Authority, and any other impacted Competent Authorities, with corrected information.

15. Jurisdictions implementing validation rules in their domestic IT system can choose different approaches: • A first approach consists of implementing all validation rules (file errors, severe record errors and other record errors) from the first year. While it implies dedicating an important amount of resources for the first implementation, it ensures data quality and consistency from the beginning. • A second approach consists of implementing for the first couple of years only the file errors and severe record errors, but not the other record errors, which allow a simpler implementation from an IT standpoint but may have as a consequence that errors concerning the quality of the data exchanged is not identified. Potential development of a common validation tool

16. As set out above, the GIR Status Message XML Schema provides for a list of validation rules to run against the GIR data but does not provide an IT tool to check such rules. Additional work is now underway to establish a common approach for ensuring data quality and consistency through common GIR validation rules.

17. Without a common IT validation tool, jurisdictions (and MNE Groups) could take different approaches to the implementation of the agreed validation rules in their IT systems. This means that the same validation rule could result in different technical requirements, risking inconsistent data submissions, exchanges and correction expectations. This could undermine the effectiveness of subsequent compliance activities, including risk assessment, and hence could translate into lower compliance levels and greater disputes in the early years of implementation.

18. Recognising these risks, work is underway to assess the possibility for developing an open-source validation tool that operationalizes the multilaterally agreed validation rules from an IT standpoint. By delivering the validation rules in open-source code format, each jurisdiction could integrate and review the source code of the tool and integrate it into its own IT environment. This approach would reduce development and maintenance burdens, particularly for developing countries, and streamline compliance for MNE Groups and tax administrations by providing uniform checks before information is filed and exchanged. Careful consideration will be given to ensure that the tool does not create discrepancies for jurisdictions that have already implemented their own system development, by ensuring coordination in the context of the WP10 Expert Sub-Group. 5.2.3. Dissemination approach Dissemination of the GIR information

19. As described in Section 5.1.2, the Dissemination Approach determines in which circumstances and to which extent specific sections of the GIR (such as the Summary Section, the General Section or one or more Jurisdictional Sections) are relevant for a jurisdiction and therefore should be exchanged with such jurisdiction, having regard to the allocation of taxing rights under the GloBE Rules. If an MNE Group makes the SbS Safe Harbour election, then only certain sections of the GIR will be provided to a jurisdiction and exchanged with impacted jurisdictions under the Dissemination Approach. For instance, if a jurisdiction has both a QDMTT and an IIR and/or a UTPR, an MNE Group that makes the SbS Safe Harbour election will provide that jurisdiction with Section 1 of the GIR (but is not required to complete Section 1.4 with the high-level summary of GloBE information) and the Jurisdictional Section for that jurisdiction. If the MNE Group chooses to centrally file in that jurisdiction, it will also provide the Jurisdictional Section for each jurisdiction with a QDMTT that has a QCAA in effect for the exchange of GIR information with that jurisdiction.

20. From the perspective of the GIR XML Schema, relevant receiving jurisdictions are identified through the ISO Codes filled in the relevant datapoints of the different sections of the Schema. Regarding the operational implementation of the Dissemination Approach, jurisdictions will rely on the identification of receiving jurisdictions made by the Filing Constituent Entity in the filed GIR.

21. Jurisdictions are encouraged to verify the proper application of the Dissemination Approach by the Filing Constituent Entity before sharing the information with partner jurisdictions, in particular by applying the relevant validation rules in this regard and by ensuring that the GIR MCAA (or an equivalent instrument) is in place between the sending and intended receiving jurisdictions.

22. In any event, the tax administration will be responsible for sorting the different Sections, and for preparing the different files to be shared with the relevant receiving jurisdictions. The tables below summarise the sections that need to be shared to the relevant jurisdictions.

Table 5. Dissemination approach for the General Section

Table 6. Dissemination approach for the Jurisdictional Section(s)

Dissemination of corrected or amended GIR information

1. Where the remediation of file and/or record errors is required, or other corrections or amendments to the GIR information are made subsequent to the initial filing of the information, the amended XML Schema file containing the (updated) GIR information received by the sending Competent Authority from the Filing Constituent Entity should be disseminated to all impacted Implementing Jurisdictions that also received the initial GIR filing pursuant to the Dissemination Approach. This is to ensure that the information is up-to-date and consistent among all Competent Authorities and that tax administration and compliance work takes place on the basis of the same GIR information at any moment in time.

2. Jurisdictions are encouraged to share the corrected information as soon as possible with receiving jurisdictions and if feasible within 90 days from the receipt of the correction request. This will allow the receiving jurisdiction to have the corrected GIR information as soon as possible and therefore be in a position to conduct the risk assessment within its domestic statute of limitation.

Best practices on the operational implementation for the exchange of the GIR information

Based on the discussions held in the context of the Amsterdam Dialogue this Toolkit includes the following guidelines for best practices on the operation of the exchange framework for the GIR: • Jurisdictions are encouraged to implement all validation rules from the first year into their IT system to ensure data quality and consistency of the exchanged GIR. • Jurisdictions are recommended to verify the dissemination approach of the filed GIR of a Filing Constituent Entity before exchanging the relevant sections with partner jurisdictions. • Jurisdictions are encouraged to develop a structured and clear correction process, to ensure that compliance takes place on the basis of the same GIR information for implementing jurisdictions. • To facilitate the operationalisation of sharing of corrected information, jurisdictions should send corrected information as soon as possible and if feasible within 90 days.

OECD Forum on Tax Administration

The Global Minimum Tax Implementation Toolkit

The Global Minimum Tax Implementation Toolkit serves as a roadmap for tax administrations and tax policy officials by setting out a series of implementation steps, each elaborated through complementary modules. It provides guidelines on best practices to tax administrations and tax policy officials on establishing efficient processes for implementing of the global minimum tax while reducing administrative and compliance burdens. Drawing on the experience of jurisdictions further advanced in their implementation journey and, including input from the business and wider stakeholder community, the toolkit identifies guidelines for best practices to support the consistent and efficient administration of the global minimum tax.