While the participation decision is discrete in a static context, i.e. to work or not to work, such is not the case in a dynamic context where workers choose the fraction of their lifetime that they spend working. In this paper, I therefore characterize the optimal redistributive policy in a dynamic environment with both an intensive and an extensive margin to labor supply. The government should optimally design a history-dependent social security system which induces higher productivity individuals to retire later. Redistribution should be done through the social security system rather than with a non-linear income tax.