Department considers that the Law N 44-FZ doesn't allow to conclude the additional agreement to the contract on extension of term of his action. The ministry already expressed similar opinion, for example, in December of last year.
The position is proved by the following. Change of terms of the contract is allowed only in the cases provided by the Law N 44-FZ. Besides, according to provisions of BQ of the Russian Federation the contract is concluded according to the scheduled plan and paid within limits of the budgetary obligations.
Document: The letter of the Ministry of Economic Development of the Russian Federation from 3/31/2017 N OG-D28-4011