EU Tax Rules Effective – But Highly Complex
Research
19.02.2026
Joint Study by the University of Mannheim, ZEW Mannheim and Ernst & Young on EU Member States’ National Discretion in Anti-Tax Avoidance
Measures to combat tax avoidance in the European Union (EU) have been expanded considerably in recent years. As a joint study recently conducted by the University of Mannheim, ZEW Mannheim and Ernst & Young (EY) shows, the national regulations differ significantly in terms of design and rigour, despite common minimum standards. The study is the first to systematically analyse how the Anti-Tax Avoidance Directive (ATAD), the EU blacklist and additional national measures have been implemented in the 27 EU Member States and how they interact with the recently introduced global minimum tax. The analysis is based on a comprehensive survey of local tax experts in all EU countries.
“Many Member States go beyond the EU’s minimum requirements. This is certainly well-intentioned and can also make tax avoidance more difficult, but it leads to large overlaps, duplicate regulations and more bureaucracy overall,” explains Professor Christoph Spengel, Chair of Business Administration and Taxation at the University of Mannheim. Sophia Wickel, a researcher in ZEW’s “Corporate Taxation and Public Finance” Research Unit, adds: “The EU has designed a detailed package of measures against aggressive tax planning. In practice, however, there is a high level of complexity due to the diversity of national tax systems.
Major differences in ATAD implementation
The analysis shows that although the EU Member States have implemented the ATAD requirements across the board, the specific aspects of the rules vary considerably. This applies in particular to controlled foreign company rules, interest barrier regulations, exemptions and thresholds. As a result, regulatory fragmentation within the EU single market is accelerating, which significantly increases legal uncertainty and administrative burdens for internationally operating companies. The question therefore arises as to whether the diversity of regulations can still be reconciled with the objective of establishing a coordinated and harmonised fiscal framework within the EU.
Interactions with the global minimum tax
Another finding is that the global minimum tax overlaps in many cases with existing ATAD measures and national anti-tax avoidance rules. Introduced as a further central instrument to combat profit shifting, the global minimum tax primarily addresses low effective tax rates. This can lead to parallel or multiple tax charges, especially in countries where legislation is already very comprehensive. The study concludes that the EU should repeal the global minimum tax and focus on the consolidation and further development of the ATAD as well as on coordinated national measures.
About the methodology
The study is based on a systematic analysis of the anti-tax avoidance regulations in force in all 27 EU Member States. In the spring and summer of 2024, a detailed survey of local tax experts with in-depth knowledge of national tax legislation was conducted. The survey was conducted in cooperation with EY’s international network and covered, among other things, the specific design of the ATAD rules, measures in connection with the EU blacklist, the implementation of the global minimum tax and additional national anti-tax avoidance measures.
