Per Unit Versus As Valorem Taxes Under Dynamic Monopoly

In the partial equilibrium framework of a static monopoly, ad valorem taxes always Pareto dominate per unit taxes. This paper shows that this result can actually be reversed in a dynamic framework where the government generates an exogenous stream of revenues through the taxation of commodities produced by a dynamic monopoly (i.e. a single producer facing dynamic demands for an intertemporal good). We show that per unit taxes Pareto dominate ad valorem taxes provided that the per period demands are relatively elastic. We provide a taxonomy concerning the Pareto dominance of the tax systems in this context and numerical examples that support our theoretical results.