Relativity, inequality and optimal taxation of internationally mobile top incomes
研究了高技能者在两国间流动时，相对消费关注（如与平均消费比较）如何影响最优劳动所得税率，发现税率随移民弹性下降，但随不平等程度或相对关注强度上升。
Abstract We use the Mirrlees income tax model with migration between two countries to investigate the optimal labour income taxation of top earners, where individuals vary in skill levels and migration costs. We consider three scenarios of relative consumption concerns: comparisons with average consumption in the population, upward comparisons and comparisons with median‐skill individuals. The tax formulas for the optimal marginal tax rate imposed on top skills are derived in closed form. Ceteris paribus, the optimal tax rate decreases with the migration elasticity of top earners but increases with the degree of inequality or the intensity of relative concerns. To explore the joint impact of these factors on the optimal tax rate, we find that even when governments prioritize the most redistributive social objective (maxi‐min), an increase in the migration elasticity of top earners weakens the demand for reducing inequality, leading to a situation where the retention and attraction of top talent take precedence over inequality mitigation. Conversely, an increase in the migration elasticity of these individuals enhances the demand for correcting positional externalities. The quantitative significance of these theoretical findings is supported by numerical examples based on parameter estimates from empirical studies.