48 CFR §32.503-11

1. (a)If a retroactive downward price reduction occurs under a redeterminable contract that provides for progress payments, the contracting officer shall—
   1. (1)Determine the refund due and obtain repayment from the contractor for the excess of payments made for delivered items over amounts due as recomputed at the reduced prices; and
   2. (2)Increase the unliquidated progress payments amount for overdeductions made from the contractor's billings for items delivered.
2. (b)The contracting officer shall also increase the unliquidated progress payments amount if the contractor makes an interim or voluntary price reduction under a redeterminable or incentive contract.