48 CFR 243.204-70-6: 243.204-70-6 Allowable profit.

When the final price of an unpriced change order is negotiated after a substantial portion of the required performance has been completed, the head of the contracting activity shall ensure the profit allowed reflects—

(a) Any reduced cost risk to the contractor for costs incurred during contract performance before negotiation of the final price;

(b) Any reduced cost risk to the contractor for costs expected to be incurred during performance of the remainder of the contract; and

(c) The extent to which costs have been incurred prior to definitization of the unpriced change order (see 215.404-71-3(d)(2)). The risk assessment shall be documented in the price negotiation memorandum .