The article is devoted to the legal analysis of the tax offense concept, as well as the inclusion of the “guilt” institution to the tax offense definition in Ukrainian Tax Code. Attention is paid to such tax offense’s qualifying features as the committing an act by person intentionally, repeatedly or in presence of the cause-and-effect relationship between the act and its consequences. It has been found that the Tax Code of Ukraine does not contain a clear definition of the “guilt” concept, but it defines the conditions under which person is found guilty. In particular, two groups of such conditions are highlighted. The first group assumes that a person who had the opportunity to comply with the norms of tax legislation did not take sufficient measures to comply with them. At the same time, the second group of conditions for finding a person guilty of committing a tax offense is the duty of the tax authority to prove that the taxpayer acted «unreasonably, in bad faith and without due diligence». However, the author emphasized that for tax authorities, the Tax Code of Ukraine establishes responsibility for committing tax offenses regardless of the presence of guilt. Special attention is paid to the characteristics of intent in the actions of a person as a qualifying feature of the tax offense. It has been substantiated that if the tax authority does not prove the fact that the taxpayer had the opportunity to comply with the tax legislation, but did not take sufficient measures to do so, such a taxpayer cannot be subject to liability measures for violating the requirements of the tax legislation. It has been noted that the confirmation of a person’s guilt can also be the commission of an ongoing and repeated offense. It has been established that the institution of guilt for tax offenses began to be applied in 2021, which was connected with the adoption of the Law of Ukraine «On Amendments to the Tax Code of Ukraine on Improving Tax Administration, Eliminating Technical and Logical Inconsistencies in Tax Legislation».