A multiple matching model with endogenous participation : what's new about the supply-side policies?

This paper aims at build a multiple matching model, in which the decision of activity on the labour market is endogeneous. Most of works on the labour market concern the only demand side. The policies applied on this side of the labour market do not consider the supply side as endogeneous. Thus, no policy can be explorated to improve the labour market situation. The supply policies seem to be the new way of action of the different governments among the European Union. In particular, in France, a policy which increases the level of earned incomes on the low wages is led since 2002, as the Earned Income Tax Credit (EITC) in the United States. This principle, called "Prime Pour l'Emploi" (PPE), is supposed to incite unskilled unemployed to take a job. In this paper, I explain that, with an endogeneous activity choice, such policies may have ambiguous effects on unemployment and social accounts. Indeed, new unemployed workers are attracted on the effective labour market by these job-taking incentives. The unemployement duration increase and the consequences on the social accounts are not obvious. Furthermore, inactivity traps phenomena can appear. I modelize the effects of an alternative policy: tax cuts on low wage associated with minimum wage increase. I show that it improves employment and production at a lower cost for the government.