The fight against tax crimes is carried out through cooperation of tax authorities with operational units of internal affairs bodies. In cooperation with tax authorities the operational units of internal affairs bodies (OVD) generally ensure the implementation of tax authorities powers to control and supervise compliance with legislation on taxes and fees. OVD are in fact participants in tax legal relations. At the same time, the insufficient development of legislation regulating these activities leads to legal uncertainty. In this regard, the authors propose to supplement Article 9 of the Tax Code of the Russian Federation with a clause fixing the status of internal affairs bodies as participants in relations regulated by the legislation on taxes and fees. At the same time, it is proposed to introduce some provisions into Articles 89–100 of the Tax Code of the Russian Federation regulating the powers and restrictions of an internal affairs body officer as a participant in an on-site tax audit. Changes in criminal, criminal procedure and tax legislation, which entered into force in 2022–2023, had a significant impact on the way economic security and anti-corruption units cooperate with tax authorities and preliminary investigation bodies in identifying tax crimes and initiating such criminal cases. Amid the changes in Federal legislation, the existing interdepartmental regulatory framework generally remains relevant, although it needs to be changed and updated. These measures are currently either unregulated or partially regulated in disparate departmental regulations of different legal force, which creates an objective need for the development and adoption of a single regulatory document. An acceptable orm of interdepartmental regulatory act may be a trilateral agreement on cooperation between the Investigative Committee of the Russian Federation, the Ministry of Internal Affairs of Russia and the Federal Tax Service of Russia. There is also a need to amend the Tax Code of the Russian Federation. It is important to eliminate the inconsistency of the current version of paragraph 3 of Article 32 of the Tax Code of the Russian Federation, which does not contain a complete list of decisions made by tax authorities to be sent so that to make a decision on initiating a criminal case. This results in a possibility of different interpretations of the relevant duty of tax authorities.