Systemic nature of the principle of legal certainty of tax law

The article examines the systemic nature of the principle of legal certainty of tax law in general and the specifics of its manifestation in Ukraine under martial law, based on domestic and foreign sources, primarily, regulations, doctrinal approaches of the Venice Commission, case law of the European Court of Human Rights, a special decision of the Constitutional Court of Ukraine, and resolutions of the Administrative Court of Cassation of the Supreme Court. The purpose of the study is to clarify the systemic properties of this principle, mainly the functions and significance of its backbone element, namely, the purpose of the principle of legal (juridical) certainty of tax law. The study focuses on the following tasks: to reveal the meaning of the understanding of the systemic nature of the principle of legal certainty of tax law by the European tradition of law cognition; to analyze the peculiarities of understanding the meaning of this principle in the Ukrainian tax law doctrine under martial law. The author has obtained the following main scientific results: tax law is a procedural system by its nature. Hence, the principle of legal certainty of tax law cannot have a different nature than tax law as a whole. According to the European tradition of tax law, the meaning of the principle of legal certainty of tax law is embodied in its purpose – to find a balance between the public interest of society and the private interest of the taxpayer in respect of the latter’s private property. In Ukraine, under martial law, a similar understanding of the principle of legal certainty of tax law is shared by the national legislator, the Administrative Court of Cassation of the Supreme Court and some representatives of the scientific doctrine of tax law. The Constitutional Court of Ukraine identifies the principle of legal certainty of tax law with the legislative basis of its stability. This is a new challenge to the principle of stability of tax law of Ukraine, which awaits its resolution under martial law.