Using the principle of equal sacrifice to evaluate a tax reform

The empirical studies evaluating the effects of personal income taxation draw their conclusions from the use of the standard statistical and redistributive indexes. Nevertheless, the Economic theory has elaborated some precise axioms to equally apportion the burden of taxation among citizens: in fact, the principle of equal sacrifice can give normative and positive contents to the ability-to-pay principle. Therefore, the purpose is to find a link between this principle and the tax progressivity: this is the only way to verify if the Personal Income Tax, as applied over the world, is consistent with Mill's approach, which has to be considered as the ultimate principle of taxation. This paper aims at discussing this main goal, first by analysing the recent theoretical outcomes and then by testing the possibility of stating that the Italian lawmaker adopts a precise criterion of distributive justice and a particular Social Welfare Function when he determines vertical equity and modifications in the Personal Income Tax structure.