National sovereignty is an attribute of the state, but also a fundamental principle of relations between states underlying cooperation.Currently, the concept of sovereignty is at the heart of the debate on tax harmonization in the European Union. In the Union, the basic principle is that each state has his fiscal sovereignty, namely the right and exclusive power to establish a system of taxation and apply it on its territory.

International double taxation is an excessive fiscal requirement on the taxpayer income and assets, representing a barrier to the movement of capital and to processes for enhancing cooperation between countries and enhancing economic and financial relations between them. For this reason states are concerned with finding solutions to avoid it, tax conventions whose provisions include the principles, criteria, methods and procedures that ...