Top income taxation: Efficiency, social welfare and the Laffer curve

This paper develops a comprehensive framework for analyzing the revenue, efficiency and social welfare implications of top income taxation. It generalizes the Saez (2001) formula for the optimal top tax rate by deriving analytical expressions for the Laffer curve and excess burden. Applied to the 2021 U.S. top federal tax bracket, assuming a taxable income elasticity of 0.25, the study finds an excess burden of $101 billion and a maximum potential revenue increase of $111 billion. In contrast, other English-speaking countries and Germany are positioned closer to their Laffer curve peaks, incurring greater efficiency losses, whereas the Nordic countries studied are on the downward-sloping part of the Laffer curve. Additionally, the paper endogenizes the marginal social welfare weight on high-income earners and, following an inverse optimal taxation approach, concludes that in none of the studied countries does the observed top marginal tax rate appear consistent with a conventional welfarist social welfare function.