Possibilities and Impossibilities for Challenging Final Tax Assessments and Decisions in Tax Cases that Contravene EC Law

When tax authorities infringe the European rights of a taxpayer, there is usually the possibility to challenge such infringement by filing an objection or appeal. However, in doing so, the taxpayer typically has to comply with domestic time limitations. Failure to do so will result in the respective decision of the tax authorities becoming final. A decision can also become final if the taxpayer did use the possibility to file an objection and appeal but his case was declined by the national highest court. As a rule, final decisions can no longer be disputed before a national court. It is, however, not uncommon that after a decision has become final, the Court of Justice (CJ) issues a ruling in a particular case, based on which the mentioned final decision turns out to be in conflict with European law. In this respect, the question arises which possibilities does EC law offer to a taxpayer to dispute a final decision of the tax authorities or a national court. In this article, the authors will analyse this question in detail and will describe the options taxpayers have in this regard. This analysis includes the validity of national time limits, obligations for administrative bodies to revisit a final decision, the impact of procedural legal effect of a decision, and the influence of the res judicata principle