Assessing the international spillover effects of capital income taxation

Changes in capital taxes by one economy spill onto other economies with internationally mobile capital. We evaluate these impacts using a two-region, intertemporal general equilibrium model. The foreign economy's unilateral reduction in corporate income taxation has positive but small effects on U.S. welfare. In contrast, unilateral reductions in personal income taxation impose large negative spillovers. The differences result from CIT being source-based and PIT residence-based. The CIT cut reduces tax burdens to U.S. residents who invest abroad, while the PIT cut reduces foreigners' tax burdens only. Through general equilibrium adjustments neglected in simpler models, the PIT cut lowers U.S. residents' welfare.