By virtue of part 13.1 of Art. 34 of the Federal law of April 5, 2013 № 44-FZ "On the contract system in the procurement of goods, works, services for state and municipal needs" the term of payment by the customer executed under the contract must be no more than 30 days from the date of signing by the customer of the document of acceptance.
Now the exceptions, when payment is made in another period, include 2 cases:
payment of small businesses or socially oriented non-profit organizations if the purchase, which resulted in a contract, was carried out exclusively among small businesses and socially oriented non-profit organizations. The payment term in such a situation is 15 working days from the date of signing the document of acceptance;
when the Government of the Russian Federation in order to ensure the defense and security of the state established a different payment term.
A new exception, which is valid from may 12, are cases where a different payment term is established by law.
Document: the Federal law from may 1, 2019 No. 71-FZ (in force 01.07.2019)