The subject. The article analyzes the legal rules of the Eurasian Economic Union (hereinafter ‘EAEU’) Member States that may potentially create barriers for access to the single market for services in the field of scientific research through establishing requirements for state registration (accreditation, licensing, etc.) of a scientific research participant. These procedures of registration (accreditation, licensing, etc.) may be relevant for the purposes of receiving the preferential tax treatment. The authors consider possible ways to overcome these obstacles. The aim of this paper is to identify typical obstacles remaining at the level of EAEU Member States’ national legislation and preventing respective participants from an access to the scientific research single market. The authors dare to identify the appropriate means of overcoming these obstacles. The methodology. The authors apply formal logical and comparative legal methods as well as analysis, literal and systematic interpretation of the domestic legal rules of the EAEU Member States and the EAEU legal framework. The main results, scope of application. The results of a comparative legal analysis of the EAEU Member States’ legislation illustrate that certain obstacles to access to the market of research services still remain within the framework of the legal systems of the EAEU Member States. Such obstacles in particular, are related to the requirements for research subjects to undergo the registration or accreditation procedure in order to receive recognition of their activities as scientific ones. Moreover, there are interconnected barriers, which consist, for example, in the requirement to not just incorporate a scientific research subject in the jurisdiction where the services should be provided, but also to register the results of the respective research activities, in particular, for the purpose of exempting these activities from VAT taxation. These barriers impede cross-border research services performance and in some circumstances do not comply with the principles of the EAEU single market of services. Conclusions. The identified barriers to cross-border scientific research can usually be overcome by directly applying the EAEU Treaty, in particular, the provisions defining the rules of the services’ single market (paragraph 38 of Annex 16 to the Treaty). The EAEU Member States’ national legislative provisions require clarification in terms of extending the national regime to scientific research subjects incorporated within other EAEU Member States.