This paper studies the optimal non linear income tax of couples. We build a general unitary model of labor supply and allow multidimensional heterogeneity in a discrete type framework. We concentrate our analysis on the resulting intra-family labor allocation of labor supplies and show that this analysis is strongly related to the choice of the tax unit (individual versus joint taxation). We give a necessary condition to have fully joint taxation in this framework and discuss some examples.

It is often argued that implicit taxation on continued activity of elderly workers is responsible for the widely observed trend towards early retirement. In a world of laissez-faire or of first-best efficiency, there would be no such implicit taxation. The point of this paper is that, when first-best redistributive instruments are not available, because some variables are not observable, the optimal policy does imply a distortion of the retirement decision. Consequently, the inducement of early retirement may be part of the optimal tax-transfer policy. We consider a model in which individuals differ in their productivity and their capacity to work long and choose both their weekly labor supply and their age of retirement. We characterize the optimal non-linear tax-transfer that maximizes a utilitarian welfare function when weekly earnings and the length of active life are observable while individuals' productivity and health status are not observable. D

This paper studies the normative problem of redistribution between individuals who differ in their lifespans. We discuss aspects related to the objective function and argue that aversion to multiperiod inequality should be taken into account. Then, we study the properties of the social optimum both with full information and with asymmetric information. We highlight the role of aversion to multiperiod inequality and show that it has substantial consequences on the design of Social Security schemes. In particular, we show that for a low (resp. high) aversion to multiperiod inequality, a negative (resp. positive) implicit tax rate on continued activity is desirable. JEL classification: D63, H55, H23, I31Mortalité différentielle et sécurité sociale. Ce mémoireétudie le problème normatif de la redistribution entre individus qui ont des durées de vie différentes. On discute certains aspects reliésà la fonction objective et on montre que l'aversionà l'inégalité sur plusieurs périodes doitêtre prise en compte. Onétudie les propriétés de l'optimum socialà la fois dans les cas d'information complète et d'information asymétrique. On souligne le rôle de l'aversionà l'inégalité sur plusieurs périodes, et on montre qu'elle a des conséquences importantes sur le design des régimes de sécurité sociale. En particulier, on montre que pour une faible (haute) aversionà l'inégalité, un taux d'imposition implicite négatif (positif) sur la continuation des activités est désirable.