Capital Gains Taxation in a Globalized World

Objective

The realization-based taxation of capital gains is often described as the Achilles’ heel of modern tax systems: it allows wealthy households and entrepreneurs to accumulate vast fortunes while deferring taxation, sometimes indefinitely or by emigrating abroad. This project studies two remedies to this weakness: accrual-based taxation and exit taxation. By combining Danish and French micro-level administrative data and frontier microeconometric methods, I aim to generate the first systematic evidence on taxpayers' response to accrual-based capital gains taxation and exit taxation. The results will have implications for how to tax capital gains in order to minimize economic distortions while reducing avoidance opportunities, raising revenue, and ultimately reducing inequality. Part 1 examines the distortions created by accrual-based taxation and compares them to distortions under the default system, where gains are taxed upon realization. In accrual-based systems, gains are taxed annually regardless of whether assets are sold. This may generate liquidity constraints, forcing taxpayers to sell assets they would otherwise have retained in order to pay their tax liabilities. By contrast, realization-based systems create a lock-in effect, whereby investors retain appreciated assets to postpone tax liability, leading to inefficient portfolio allocation. Using Danish administrative data, I will present direct empirical evidence on the prevalence of both distortions. Part 2 focuses on exit taxation, which levies taxes on accrued gains when taxpayers emigrate. By discouraging the emigration of wealthy households, exit taxation may protect the domestic tax base and support innovation and employment. Despite its substantial policy relevance, there is to date no empirical evidence on its impact. Leveraging French administrative data and the exit tax reforms of 2011 and 2014, I will estimate how exit taxation affects the semi-elasticity of migration with respect to taxation.