A popular proposal for reforming social security is to supplement or replace traditional publicly financed benefits with a new system of mandatory defined-contribution private pensions. Proponents claim that private plans offer better returns than traditional social security. To achieve higher...

Pension benefit rules depend on individual history far more than taxes do, and age plays a much larger role in pension determination than in tax determination. Apart from some simulation studies, theoretical studies of optimal tax design typically contain neither a mandatory pension system nor...