Notwithstanding the efforts to harmonize and coordinate European tax states, by building insights from the fiscal governance rules, EU taxation is still far from being linked to the idea of homogeneous and is a little appetite to proceed further on the path of fiscal integration. While some papers tend to focus and debate on marginal issues and unrealistic proposals regarding the idea of "fiscal union", rather than helping to consolidate a realistic literature background on European integration, by taking into consideration fiscal sustainability, fiscal sociology and political economy, is deepening the gap of literature and distances the European decision-making poles from feasible targets. Given that tax reforms may differently affect specific countries and EU states reflect differences in their tax systems, fiscal consolidation and some form of fiscal integration is still required to achieve a sustainable solution in terms of fiscal coordination, democratic legitimacy and long-term sustainability. The first section of the paper is dedicated to a critical review of existing scientific evidence regarding the heterogeneity of European countries' taxation systems and the idea of "fiscal union". The second part focuses on analysing the repeated efforts of the European Authorities to harmonize countries taxation, pointing the existing differences in terms of taxation and linked this to the requires of improving fiscal governance, identifying new challenges in order to maintain fiscal stability and to consolidate Europe's economies.