Pillar Two is the OECD's global minimum tax framework - a 15% floor on the effective tax rate of large multinational enterprises in every jurisdiction where they operate. Over 140 countries have agreed to implement it. The US has not enacted a domestic Pillar Two regime. Instead, the US has the Corporate Alternative Minimum Tax (CAMT) at 15% and an expanded BEAT, which overlap partially with Pillar Two but are not equivalent. US multinationals with operations in Pillar Two jurisdictions face foreign top-up taxes on their low-taxed income, and some jurisdictions are threatening to impose the Undertaxed Profits Rule (UTPR) as a backstop against the US non-adoption - effectively taxing US parent companies in foreign subsidiaries' countries.
Scope: Applies to MNE groups with consolidated annual revenue of EUR 750 million or more in at least two of the four preceding fiscal years.
Income Inclusion Rule (IIR): The parent jurisdiction taxes the parent on its share of low-taxed income of its subsidiaries. Applied top-down - the ultimate parent country has first right to collect the top-up tax.
Undertaxed Profits Rule (UTPR): A backstop rule applied in subsidiary jurisdictions when the IIR is not applied by the parent country. If the US does not implement an IIR, foreign subsidiaries of US parents in UTPR-adopting countries may face a top-up tax on the US parent's low-taxed income - effectively collected from the US company's foreign operations.
QDMTT: A Qualified Domestic Minimum Top-Up Tax - a country's own 15% minimum tax on its resident companies. A QDMTT satisfies Pillar Two obligations domestically, preventing other countries from topping up under the IIR/UTPR.
The Pillar Two effective tax rate (ETR) is not the same as the ETR under US GAAP or any domestic tax measure. It is calculated jurisdiction by jurisdiction using the Pillar Two GloBE (Global Anti-Base Erosion) rules. GloBE income is derived from the financial accounting income with specific adjustments. Covered taxes include current and deferred income taxes with limitations - certain deferred tax adjustments are excluded or capped. The ETR equals covered taxes divided by GloBE income. If the ETR in any jurisdiction falls below 15%, a top-up tax is imposed on the difference.
The Substance-Based Income Exclusion (SBIE) carves out from the GloBE income base a formulaic return on payroll and tangible assets in each jurisdiction. This exclusion reduces the top-up tax burden for companies with significant physical presence in low-tax jurisdictions - rewarding genuine economic substance and penalizing IP box structures with little real activity.
The US enacted a 15% Corporate Alternative Minimum Tax (CAMT) under OBBBA P.L. 119-21, applying to corporations with average adjusted financial statement income exceeding $1 billion. The CAMT is calculated on adjusted book income - closer to Pillar Two GloBE income than the traditional AMTI. However, the CAMT is not a Qualified Domestic Minimum Top-Up Tax under Pillar Two because it applies to global income rather than a jurisdiction-by-jurisdiction calculation, and its design deviates from the GloBE rules in several respects. The US has not enacted an IIR or a QDMTT. Congress has been resistant to Pillar Two adoption, viewing it as an erosion of US tax sovereignty.
US MNEs in scope should be doing the following now: (1) Run a jurisdiction-by-jurisdiction Pillar Two ETR analysis to identify where top-up taxes will be triggered; (2) Model the SBIE to quantify the carve-out for payroll and tangible assets; (3) Identify which subsidiaries are in Pillar Two-implementing jurisdictions that have enacted the UTPR; (4) Assess the CAMT's interaction with Pillar Two taxes - foreign Pillar Two taxes are likely creditable against CAMT but the mechanics are complex; (5) Review IP structures and financing arrangements that produced low jurisdictional ETRs - those arrangements are exactly what Pillar Two targets and the economics have shifted.