This ZATCA Simplified Guide (Version 1, 29 June 2022) gives taxpayers a non-technical overview of e-invoicing requirements in the Kingdom of Saudi Arabia. It defines key terms such as e-invoice, Tax Invoice, Simplified Tax Invoice and QR code, and sets out the timeline: the Generation phase from 4 December 2021 and the Integration phase from 1 January 2023, enforced in waves with at least 6 months' notice. It walks through the Phase One and Phase Two invoice flows, including reporting of Simplified Tax Invoices to ZATCA within 24 hours and clearance of Tax Invoices, the QR code components and scanning, practices to avoid, prohibited functionalities, how to prepare, and onboarding a solution through the Fatoora portal with an OTP.