OPTIMAL INCOME TAXATION,DYNAMIC EFFICIENCY,AND THE SOCIAL COST OF PUBLIC EXPENDITURE*

An interest income tax and a publicly provided private good are introduced into the Hamada overlapping-generations model consisting of heterogeneous individuals where the government can use a wage-income tax, an identical lump-sum transfer, and the public debt. Two interesting problems are studied: (a) what relation exists between the optimal interest rate and the population-growth rate and (b) how dynamic efficiency affects the optimal-decision rules of taxes and the publicly provided good. We show that (i) if the government can (not) tax the interest income, then the optimal interest rate is (not) equal to the population-growth rate, (ii) without the availability of the interest tax the difference between these two rates is mainly caused by the income-distribution effect of the public debt and (iii) the dynamic efficiency effects on the optimal rules of the wage tax and the publicly provided good depend on not only such a difference but also the average substitute-complement relations among leisure, the second-period consumption and the publicly provided good.