In light of the principle of additionality, the inflow of European Union (EU) funds should complement domestic public funds, which are required to cofinance the investment. EU funds should either be unrelated to fiscal decisions of recipient regions, and as such should not affect taxation choices, or they could imply an increase in taxation to finance the additional domestic funds required by the additionality principle. Empirical results linking fiscal autonomy of Italian regions, considered by looking at the number and the level of average tax rates for the regional surcharge on the personal income tax and committed EU funds, suggest the existence of a significant relationship, even after controlling for relevant economic and political factors. The level of average tax rates is lower the more EU funds are received, as is the complexity of the system, measured by the number of income tax brackets
