<P>This book discusses which is the most appropriate tax dimension to best manage the new horizons of the global and digital economy. </P><P>In this perspective, the efficiency of the main models is examined and two fundamental proposals are put forth: the first one aims at a coordination of the Destination-Based approach with the role of some specific digital assets, such as user data; the second one is a framework for a possible futuristic tax phenomenon all internal to the world of the internet and not linked to traditional territorial States. The compliance of these models with the constitutional principles that western democratic systems have affirmed over time in matters of taxation is then analyzed with particular regard to legal certainty, consent to taxation and to the re-distributive function of taxes. A specific evaluation of the role of the European Union is carried out and the jurisprudence on financial interests of the Union and on State aids is analyzed and tackled in li