How to fight against tax fraud?

Summary Tax evasion is a subject that eludes the tools of traditional economic analysis. On the one hand, like any illegal activity, tax evasion escapes the researcher's observation while at the same time hiding from the authorities: empirical analysis of its scope, its determinants and the way in which different mechanisms affect it is necessarily very limited. On the other hand, from a theoretical point of view, the simple application of the cost-benefit calculation that the "rational" taxpayer is supposed to make leads to a paradox: contrary to a widely held idea, the benefits of tax evasion are so high, and the risk of punishment so low, that it is surprising that it is so little practiced in all developed economies. Rather than tax evasion, it is therefore "tax compliance" that constitutes its counterpart, the willingness to pay tax, that needs to be explained in order to understand its determinants. The double challenge that tax evasion decisions pose to economic analysis has only recently been met, thanks to the emergence, over the last twenty years, of a new approach, behavioral economics, which relies on psychology to better understand economic behavior. And, at the same time, of a new method, experimental economics, which allows for the empirical study of economic behavior on which it is difficult to collect convincing data. This booklet reports on the results of this work and presents an overview of the tax policy tools that have emerged from it.