Sowiński, Ryszard2013-03-112013-03-112003Ruch Prawniczy, Ekonomiczny i Socjologiczny 65, 2003, z. 3, s. 5-160035-9629http://hdl.handle.net/10593/5086The article examines the issue of tax base estimation, crucial from the theoretical standpoint as well as for practicalities of tax law application. The paper focuses on the analysis of legal regulations adopted in the Tax Law, unfolding the legal origin of the current provisions and explaining the grounds and reasons for their application. The author presents literature on the subject of tax base estimation relying on the decision of the Supreme Administrative Court, explains the methods used in tax base estimation and assesses the legitimacy of introduction of tax base estimation institution to the Polish tax system. The author argues that the rule of definability of legal regulations requires clear-cut rules on taxation. On the other hand, imposing rigid norms concerning tax base estimation on tax institutions is difficult to accept. The complex nature of economic processes calls for some freedom in decision-making by tax institutions since only then can the rule o f material truth be truly implemented.plArtykuł