The United States became the first BEPS Inclusive Framework member to formally adopt any portion of Pillar One in its domestic law when, in December 2024, the US Internal Revenue Service issued Notice 2025-4 effectively adopting Amount B. The impact of this attempted reassertion of global tax policy leadership will depend on whether and to what extent taxpayers and other jurisdictions follow. Forthcoming IRS regulations on Amount B could incentivize them to do so.