• Legal definitions for tax avoidance and substance • Hierarchy and interaction of anti-avoidance rules: domestic General Anti-Avoidance Rules, Special Anti-Avoidance Rules, Multilateral Instrument (Principle Purpose Test), Anti-Avoidance Tax Directive • Safe harbour rules for substance • The role of tax rulings • The boundaries in the ECJ case law and general principles of international law The panel will – with reference to examples – discuss the impacts of the current conundrum of the anti-avoidance provisions, their interaction and potential inconsistency with domestic general anti-avoidance rules and specific anti-avoidance rules. In particular, the panel will cover the new anti-avoidance provisions in the form of the principle purpose test as the minimum standard under the Multilateral Convention, the general anti-abuse rule of both Anti-Tax Avoidance Directive 1 and 2, the role of the principle of economic substance and the boundaries set by recent ECJ cases and by the general principles of international law. The panel will also focus on the role of tax rulings for achieving legal certainty.