This paper reviews studies that attempt to empirically measure revenue gains from tax harmonisation. Three groups of studies emerge: those that use cross-country regression, partial equilibrium analysis, and applied general-equilibrium (CGE) models. They all suggest (explicitly or implicitly) that the relationship between tax rates and tax revenues is ambiguous.

Key findings:

In some special circumstances, there are gains that can be realised from tax harmonisation, but those gains are usually modest in scope. Tax harmonisation tends to disadvantage certain countries, especially when the participating countries differ in size and when disparities in their initial tax structures are wide.