Second-best income taxation and education policy with endogenous human capital and borrowing constraints

We formulate a two-period life cycle model of saving, labor supply, and human capital investment when individuals differ in their ability and initial wealth. Borrowing constraints result in sub-optimal choices for consumption and investments in human capital. We analyze optimal linear income taxes and education subsidies. The optimal income tax is shown to be positive—even in the absence of any redistributional concerns. A redistributive income tax relaxes borrowing constraints by redistributing resources from the unconstrained to the borrowing constrained stages of the life cycle. The income tax thus alleviates preexisting non-tax distortions in the capital market. Human capital is subsidized on a net basis in the absence of redistributional concerns. Education subsidies help to relax credit constraints and to reduce distortions from explicit and implicit taxes on human capital formation. When redistributional concerns are present, education is subsidized more if this helps to alleviate distortions on labor supply, but is subsidized less if education subsidies have a very regressive incidence. Simulations demonstrate that optimal income taxes are substantially higher when credit constraints are present. Education is generally subsidized on a net basis, and the more so if credit constraints are more severe.