Welfare-enhancing taxation and price discrimination

We study commodity taxation in markets where suppliers implement second-degree price discrimination, by offering different package sizes or quality-differentiated versions of a product. In these markets, suppliers distort the quantity (or quality) intended for all types of consumers, except for those with the highest marginal willingness to pay. We show that differentiated ad valorem taxes can alleviate this distortion, and thus increase government revenue as well as welfare, provided the tax rate increases with the size of the package (or quality of the version) of the good supplied.