This article gives an overview over the solidarity contribution of Regulation 2022/1584 with a focus on its implementation in Germany and provides economic background on the taxation of excess profits. In a second part, the competence of the EU is critically assessed, especially the applicability of Article 122 TFEU with its limited role of the European Parliament. Alternative competence norms are explored. Additionally, the competence under German law is explored. The third part scrutinizes, whether the solidarity contribution or similar excess profits taxes infringe the freedom of enterprise or occupation or equal treatment rights, both under European and German law. Finally, the retroactive application of the solidarity contribution is examined under EU and German constitutional law.