The Directive (EU) 2021/2101 of the European Parliament and of the Council of 24 November 2021 amending Directive 2013/34/ EU as regards the public disclosure of income tax information by certain undertakings and branches, entered into force on 21 December 2021 and must be implemented by all EU Member States until 22 June 2023. It introduces the so-called ‘Public Country- By-Country Reporting’ system in the European Union. With these new transparency rules, the EU seeks to raise greater public scrutiny on the tax planning practices carried out by certain undertakings with activity in the EU. Despite its many achievements, the directive has several shortcomings, namely in what concerns compliance with legal certainty, issues in its implementation and effectiveness for achieving its ratio legis. After mapping these issues, we will put forward proposals that could be adopted by either the European or domestic legislator (the latter, at the implementation stage).