The subjects of small and average business (SSAB) participating in purchases under the Law No. 223-FZ have to declare the status, providing the information from the unified register of subjects of small and average business. At purchase implementation the customer has the right to establish the requirement to such subjects about inclusion of the declaration on belonging to SMSP or data from the unified register of SSAB in structure of the application for participation in purchase. Besides, at the conclusion of the contract with the participant of such purchase the customer has the right to carry out check of compliance of this procurement participant to the criteria established by article 4 of the Federal law "About Development of Small and Average Business in the Russian Federation" on the basis of data from the unified register of SSAB.