The study focuses on the current issues related to adjudication on matters of preferential rates of duty on fuel oil. Polish legislation gives the possibility of preferential taxation of fuel oil sales, provided that numerous conditions are met. In order to take advantage of the preferential tax, the taxpayer must inter alia, obtain a statement from the purchaser of oil that the goods are purchased for heating purposes (‘fuel statement’). Initially the legal requirements for fuel statements were set in a form of regulations issued on the basis of the provisions of the Law on excise duty. is practice caused much controversy as to the compliance with the Polish Constitution. For this reason, these regulations were, and still are a subject of the question of law submitted to the Constitutional Court. Moreover, such regulations are to be interpreted and applied in individual cases by administrative courts. The administrative courts, while resolving cases, indicate the purpose of the regulations and their importance to the outcoming of the case. is paper describes the current state of adjudication in matters of fuel statements. The study focuses on the consequences of the defective statement of fuel in the sphere of substantive law. Initially, the case-law was not consistent. There were different views as to the importance of the fuel statements in tax proceedings. Because of the doubts of compliance with the Constitution of the Republic of Poland of the provisions related to statements of fuel, in several cases the courts decided to suspend the proceedings and submit a question of law to the Constitutional Court. Final settling of the question of the constitutionality of these provisions by the Constitutional Court’s ruling issued on 7 September 2010, Ref. P 94/08, publ Z.U. 2010/7A/76 means that the proceedings have to be resumed. So far, only few of such cases were resolved by administrative courts’ ruling. The paper also comments the current law related to the statements of fuel.