Under Pillar Two, the OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting members have agreed to enact a jurisdictional-level minimum tax system with a minimum effective tax rate of 15%. Multinational enterprises and EU-based large-scale purely domestic groups with (global) consolidated turnover above EUR 750 million will be within the scope of Pillar Two. In this article, the authors discuss the relevant rules for calculating the effective tax rate (ETR) under Pillar Two. Subsequently, the authors will compare these rules with the rules that are applied to calculate the ETR under financial accounting. The main aim of this article is to set out the key differences between the ETR calculation under Pillar Two and financial accounting. For the comparison, the authors take the International Financial Reporting Standards (IFRS) as the applicable accounting standard under financial accounting.