The subject. Currently, the courts are actively using a new term - "valid tax liability", or "the actual amount of tax liabilities". This term is the result of the activities of judicial authorities, however, judicial practice on determining the actual tax liability for personal income tax is only being formed and is unstable. Therefore, the subject of the study of this article is a comprehensive analysis of law enforcement practice in the field of determining the actual tax liability of individuals for personal income tax.Purpose of the study is to dare to solve the enforcement problems that arise when determining the actual tax liability of individuals for personal income tax.The methodology. The authors uses the formally legal interpretation of Russian legislation, comparative analysis of Russian and European literature as regards the determination of a valid tax liability.The main results, scope of application. The authors analyzed the concept of "valid tax liability", and also studied the problems of determining the actual tax liability in the context of the law enforcement practice of the Supreme Court of the Russian Federation. Based on law enforcement practice, the main problems in determining the actual tax liability are highlighted, to which the authors attribute the incorrect qualification of the object of taxation, the incorrect qualification of the nature of the taxpayer's activity and its status, as well as the incorrect determination of the taxpayer's tax base. The article also touches on the main problems in the reimbursement of the amount of overpaid personal income tax.Conclusions. When determining the taxpayer's actual tax obligation to pay personal income tax, the tax authorities are guided by a "pro-budget" goal, seeking to increase the tax base due to incorrect qualification of the taxable object, the status of the taxpayer, or questioning the nature of its activities, which leads to the formation of arrears and forms the composition of an administrative offense.In an effort to restore their violated rights, an honest taxpayer goes to court for protection, where, unfortunately, in the vast majority of cases, they face the formal approach of the courts, which do not reveal either the economic essence of the dispute or properly consider the circumstances of a particular case. Taking into account the above circumstances, the authors draw conclusions about the existence of legal gaps in the system of Russian law in the field of taxation, which they propose to fill by fixing the concept of "valid tax obligation" in the relevant Resolution of the Plenum of the Supreme Court of the Russian Federation. As an example of such replenishment, the authors propose to supplement paragraph 7 of the Resolution of the Plenum of the Supreme Commercial Court of the Russian Federation of October 12, 2006 No. 53 "On the assessment by arbitration courts of the validity of the taxpayer's receipt of tax benefits", indicating the need to establish a valid tax obligation of the taxpayer, including personal income tax.