Consumption taxes in monopolistic competition: a comment

We show that an ad valorem tax is better than an equal-revenue unit tax when consumers spend some fixed proportion of income on taxed goods, when firms use constant mark-up pricing, and entry and exit drive per-firm profit to zero. These key assumptions implies that ad valorem taxes are superior in oligopoly as well as monopolistic competition, showing that earlier results on taxes in monopolistic competition (Schroder in J Econ 83(3):281-292, 2004) are not due to the mode of competition, but rather are due to the functional forms used.