The topic of tax authorities is essential from both theoretical and practical perspectives. It encompasses a variety of questions related to the fundamental features of these institutions and to the identification of comprehensive regulations for establishing their competency. Additionally, it holds particular importance regarding taxes since tax liability arises following the delivery of a constitutive decision by such an entity (a decision that determines the amount of tax liability). These premises facilitate an in-depth examination of the legal measures relevant to this case. Thus, the research presented here encompasses the relevant statutes, an implementing act, and the perspectives of legal scholars and commentators. Special attention is paid to the judiciary’s stance. The conclusions drawn from this study are useful for formulating de lege lata and de lege ferenda recommendations.