The subject of the study is the legal regulation of the obligation to use cash registers and its relationship with the tax obligation, as well as the ratio of tax control and control over the use of cash registers (operational control).The purpose of the study is to determine the theoretical, practical and legislative (normative) approaches to the integration of relations for fixing settlements (including with the use of cash registers) in the sphere of tax legislation regulation. The author determined the place of relations in the field of application of cash registers in the system of tax legal relations.The main hypothesis proposed by the author is that Russian legislation lacks the required quality of a legal link between the use of cash registers and the payment of taxes. According to the Tax Code of the Russian Federation, the obligation to use cash registers is not the responsibility of the taxpayer. At the same time, the obligation of organizations and individual entrepreneurs who make settlements in the Russian Federation is enshrined in a separate legislative act. This act establishes that the use of cash registers is carried out, among other things, for tax purposes, and the tax authorities are vested with the appropriate powers to control the use of cash registers.The author emphasizes that the use of a cash register is a tool for fixing the calculation - documenting in the trusted zone of the state the fact of the financial and economic life of the taxpayer. The nature of the obligation to use cash registers is the nature of tax legal relations. Although liability for violation of the rules for the use of cash registers under Russian law is administrative in nature, this fact does not contradict the theory of law. Consequently, the transformation of administrative responsibility for violation of the rules for the use of cash registers into tax liability is optional.In this regard, it is necessary to implement legislative changes in order to integrate into the tax legislation relations on the use of cash registers and control over the use of cash registers. The author, citing foreign legislation as an example, points to various options and degrees of integration. As the best option, it is proposed to include the obligation to record settlements in the Tax Code of the Russian Federation and recognize operational control as part of tax control there.In the course of the work, the author used both general research methods, including methods analysis and synthesis, as well as industry, including the formal legal method.Based on the results of the study, the author comes to the conclusion that it is necessary to transform the approach to the use of cash registers, to move to the category of “fixing settlements”. The necessity of including operational control in the composition of tax control is emphasized. This fact will create a single set of tools and rules for the work of tax authorities. All of the above will lead to the fact that each specific fact of violation of the rules for the use of cash registers can be reflected in a desk or field tax audit. As a result, the obligation to fix the calculations will become the basis for the functioning of new and promising taxation regimes.