Optimal income taxation, incentive constraints, participation constraints.

Summary This thesis is based on the theory of optimal income taxation developed by Mirrlees. It seeks to better understand the consequences of incentive constraints in a closed economy and the nature of the interactions between incentive and participation conditions in an open economy. Chapter 1 develops the comparative statics of the optimal income tax problem with a discrete population and quasi-linear preferences in consumption. Chapter 2 studies the proposed tax schedule developed by Kolm (2004) in the light of optimal taxation theory. Chapter 3 presents the main models of optimal income taxation that allow us to identify the impact of tax mobility for the most competent agents. Chapters 4 and 5 introduce type-dependent participation constraints in linear and then non-linear optimal taxation problems to assess the effects of individual mobility.