The environment of EU tax policy has fundamentally changed in recent times. As a reaction to the European debt crisis new fiscal instruments (EFSF, ESM), new fiscal rules (Fiscal Compact) and coordination procedures (European Semester) have been established. These open new channels of Community influence on formerly autonomous fields of national policy. With this background it is the overriding objective of the network to provide a fundamental contribution to an integrated theory and empirics of European tax harmonization under this new institutional environment. Within this general objective questions like the following will be addressed: How is the past path of European tax harmonization explainable? How will the mentioned new fiscal institutions impact on tax harmonization? Will the budgetary shock which has occurred as a consequence of the financial and the debt crises change the tax competition equilibrium in Europe? How would new compensatory instruments within the EU budget influence the perspective of tax harmonization if these new instruments would offer an equalization of distributive effects which may result from harmonization steps? What would be the effects of specific tax harmonization concepts like for example a harmonized corporate tax base as it is promoted by the European Commission (CCCTB = Common Consolidated Corporate Tax Base)?