Optimal Tax Policy under Environmental Quality Competition

This paper studies the socially optimal emission and commodity tax policy when consumers are willing to pay a price-premium for environmentally friendlier variants of a commodity vertically differentiated in environmental quality. The first-best levels of quality can be obtained by a combination of a uniform ad valorem tax and an emission tax (or a subsidy for buying green products). The first-best emission tax is higher than the social valuation of the positive externality associated with average environmental quality. Regardless of environmentally conscious consumers, if only one instrument is available, the second-best emission tax is equal to the social valuation of the positive externality associated with average environmental quality. A uniform ad valorem tax increases welfare only if the social valuation of the positive externality associated with average environmental quality is low enough.