Public debt can be optimal in standard incomplete market models with infinitely lived agents, since the associated capital crowd-out induces a higher interest rate. The higher interest rate encourages individuals to save and, hence, better self-insure against idiosyncratic labor earnings risk....

This paper considers the impact of endogenous human capital accumulation on optimal tax policy in a life cycle model. Including endogenous human capital accumulation, either through learning-by-doing or learning-or-doing, is analytically shown to create a motive for the government to use...