In EU competition law, the concept of economic activity is governed by a functional approach whereby for an entity to be considered an undertaking it must provide services for remuneration in a market context, albeit only potentially. With regard to social security and healthcare, the article argues that there is uncertainty as to whether the aforesaid approach has been endorsed by the EU institutions. Today, exacerbating this uncertainty are conflicting trends in the case law of the CJEU and the practice of the European Commission on the relevance of the principle of solidarity in assessing Member States’ laws and regulations. This uncertainty should be remedied by the two institutions taking a clear stance on the issue. In this respect, better advantage could be taken of Article 106(2) TFEU as a balancing tool.