This paper develops a quantitative general-equilibrium model to analyze the macroeconomic implications of a global minimum corporate income tax for the U.S. economy. This policy has been widely adopted by some of the United States’ most important trade partners, including the European Union and Japan, under a landmark international agreement spearheaded by the OECD and the G20, but the United States itself has not yet implemented it. This inaction poses questions about the policy’s potential macroeconomic impact given the United States’s status as the domicile of the world’s largest multinational enterprises (MNEs) and its position as the global economic leader. Our model features heterogeneous firms that make endogenous decisions about exporting, multinational production, and profit shifting, as well as a detailed representation of MNE-related provisions of the U.S. tax code, including the GILTI provision of the 2017 Tax Cuts and Jobs Act (TCJA). Through a series of counterfactual analyses, we quantify the macroeconomic consequences of TCJA’s MNE-related provisions, the unilateral implementation of a global minimum corporate income tax by the U.S.’s main trading partners, and the interaction between these effects. Additionally, we evaluate the potential effects of the U.S. adopting such a policy. Our findings shed light on the complex dynamics at play and offer critical insights into the potential paths forward for U.S. policy in the context of global tax reform.