According to article 4 of the Soldarity Tax Law, a taxpayer of the solidarity tax is a taxpayer of the income tax in accordance with the Corporate Income Tax Law. The taxpayers were obligated to calculate the tax base according to article 6 and submit tax declarations to the Public Revenue Office no later than 25 September 2023—the date the law both entered into force and was officially published. The law’s immediate effect and retroactive scope sparked significant legal debate. Although rooted in principles of solidarity, fairness, and social responsibility, the implementation of the Law raised serious constitutional and legal concerns, particularly regarding the principle of non-retroactivity. This principle, as a cornerstone of tax law and the broader rule of law, ensures legal certainty and predictability for taxpayers. The Law’s retroactive nature violated the legal principle that laws should not take effect before their official enactment, especially in cases where they impose financial obligations. Furthermore, the law challenged foundational legal doctrines such as justice, proportionality, legal predictability, and legal certainty
Kristina Miseva (Thu,) studied this question.