Lex retro non agit Aule in Tax Law - Comments Evoked by the Case K 4/19

The rule saying that the law has no retroactive force (lex retro non agit) is of particular importance in tax law. Generally, it is recognized as a measure protecting taxpayers’ rights. Local government units evoked this rule in the case K 4/19 examined by the Constitutional Tribunal. From this point of view, we deal with the situation that is both practically and theoretically significant. The legislator used retroactive force of law to amend provisions imposing a real estate tax on wind farms, which decreased taxpayers’ liabilities but, at the same time, municipal own income. A purpose of the study is to present the above-mentioned issue and answer the question whether the above quoted rule was actually violated. The analysis of its factual and legal aspects apparently entails that it did occur. To prove it, the author of the study has mainly used a formal-dogmatic research method based on the analysis of the Constitutional Tribunal case law and the subject literature.