The work presents the results of studying the interpretation problems of Article 54.1 of the Tax Code of the Russian Federation and its application by Russian courts. The main issue highlighted in the work is the legal grounds for applying the article retroactively in the absence of a clear legislative regulation of its operation in time. To find a solution of the problem below, the author analyzed the provisions of Article 54.1 from the point of its content, legal nature, target orientation and influence on the first law enforcement practice. A study of the legal positions of courts has shown that most decisions do not rely on any analysis of the provisions of the article and the refusal in its application is usually supported by a minimal legal justification. At the same time, deciding on the issue of retroactivity, article 54.1 requires an in-depth analysis of its content in terms of improving or worsening the position of the taxpayer in connection with its adoption. Thus, the established judicial practice