48 C.F.R. § 42.1303 – Stop-work orders.

(a) Stop-work orders may be used, when appropriate, in any negotiated fixed-price or cost-reimbursement supply, research and development, or service contract if work stoppage may be required for reasons such as advancement in the state-of-the-art, production or engineering breakthroughs, or realignment of programs.
(b) Generally, a stop-work order will be issued only if it is advisable to suspend work pending a decision by the Government and a supplemental agreement providing for the suspension is not feasible. Issuance of a stop-work order shall be approved at a level higher than the contracting officer. Stop-work orders shall not be used in place of a termination notice after a decision to terminate has been made.
(c) Stop-work orders should include—
1. (1) A description of the work to be suspended;
2. (2) Instructions concerning the contractor's issuance of further orders for materials or services;
3. (3) Guidance to the contractor on action to be taken on any subcontracts; and
4. (4) Other suggestions to the contractor for minimizing costs.
(d) Promptly after issuing the stop-work order, the contracting officer should discuss the stop-work order with the contractor and modify the order, if necessary, in light of the discussion.
(e) As soon as feasible after a stop-work order is issued, but before its expiration, the contracting officer shall take appropriate action to—
1. (1) Terminate the contract;
2. (2) Cancel the stop-work order (any cancellation of a stop-work order shall be subject to the same approvals as were required for its issuance); or
3. (3) Extend the period of the stop-work order if it is necessary and if the contractor agrees (any extension of the stop-work order shall be by a supplemental agreement).