Rules intended to prevent tax avoidance often place the burden of proof on the taxpayer. Such an allocation of the burden of proof is incompatible with the case law of the Court of Justice of the European Union (ECJ). In this article, the authors provide examples of Netherlands and Italian tax laws that are in breach of the allocation of the burden of proof as prescribed by the ECJ. As these examples concern types of rules applied in other EU Member States, the authors expect that there will be similar issues in many other EU Member States.