The issue related to countering tax avoidance has become one of the most significant problems that is being analysed not only by individual EU Member States but also the European Commission. One of the most common solutions is the ATAD Directive (Anti-Tax Avoidance Directive) that refers to the activity of OECD as part of the BEPS project (i.e., Base Erosion Profit Shifting). The paper presents not only the directions of changes in the Act on CIT in the context of implementation of these EU regulations but also the aspects of countering tax avoidance that are emphasised by the judicial decisions of the Court of Justice of the European Union. What is more, the paper shows the main reasons for adopting the ATAD Directive, which, on the one hand, correspond to the reasons behind each BEPS action (countering tax base erosion) and, on the other hand, justify the adoption of these regulations from the perspective of acquis communautaire.