Optimal taxation for polluting oligopolists with endogenous market structure

This paper examines the optimal output taxes for polluting oligopolists under endogenous market structure, in the presence of external costs that vary exogenously with aggregate output. For general functional forms, we show that (i) the equilibrium number of firms in an industry may differ from the socially optimal number of firms and (ii) the second-best optimal taxes under imperfect competition could be less than, equal to, or greater than marginal external damages depending upon the curvature of market demand.