Tax uniformity: A commitment device for restraining opportunistic behaviour.

We investigate whether and to what extent uniform and differentiated tax systems diverge in their propensity to create distortionary opportunistic behavoiur. The set-up in which we carry out our analysis features polluting firms that are confronted with existence a Pigovian emission tax. Firms can invest in pollution abatement. We first show that the existence of emmission taxes, although optimally chosen, create strategic incentives for firms to distort their abatement investment. Second, we find that a system of differentiated emission taxes has a greater propensity to foster strategic distortions in abatement investment than a uniform emission tax regime.