A welfare comparison of ad valorem and unit tax regimes

This paper strives to merge two strands of the literature. The first group of papers compares ad valorem and unit taxes in a tax competition framework in terms of welfare. The second group of papers regards capital income taxes as a conjunction of taxes on pure profits and taxes on capital income. We find that, given decreasing returns to scale, there always exists a level of the share of deductible capital costs strictly smaller than one, such that for all values larger than this threshold, an ad valorem tax regime unambiguously Pareto-dominates a unit tax regime.