Laurent Simula

Optimal Non-Linear Income Tax when Highly Skilled Individuals Vote with their Feet

This paper examines how allowing individuals to emigrate to pay lower taxes changes the optimal non-linear income tax scheme in a Mirrleesian economy. Type-dependent participation constraints are borrowed from contract theory. An individual emigrates if his domestic utility is less than his utility abroad net of migration costs, utilities and costs both depending on productivity. Three social criteria are distinguished according to the agents whose welfare matters. Mobility significantly alters the closed-economy results qualitatively, but also quantitatively as veri.ed by simulations. A curse of the middle-skilled occurs in the first-best. In the second-best, the middle-skilled can support the highest average tax rates and the marginal tax rates can be negative. Moreover, preventing emigration of the highly-skilled is not necessarily optimal.

Optimal Linear Income Tax when Agents Vote with their Feet

Individuals, initially living in a Mirrleesian economy A, have outside options consisting in settling down in a laissez-faire country B while paying positive migration costs. We first examine the effect of the threat of migration, assuming participation constraints are taken into account for all individuals, and show that optimal linear income taxes are obtained as corner solutions. We then consider a social criterion allowing emigration of the highest-skilled individuals and show by means of an example that social welfare may rise following an increase in income redistribution, despite this resulting in the departure of the most productive individuals. Numerical simulations on French data illustrate the lack of degrees of freedom offered by linear taxation when agents can vote with their feet, which may be regarded as an argument against linear taxes.