48 C.F.R. § 49.112-2 – Final payment.

(a) Negotiated settlement. After execution of a settlement agreement, the contractor shall submit a voucher or invoice showing the amount agreed upon, less any portion previously paid. The TCO shall attach a copy of the settlement agreement to the voucher or invoice and forward the documents to the disbursing officer for payment.
(b) Settlement by determination. If the settlement is by determination and—
1. (1) There is no appeal within the allowed time, the contractor shall submit a voucher or invoice showing the amount determined due, less any portion previously paid; or
2. (2) There is an appeal, the contractor shall submit a voucher or invoice showing the amount finally determined due on the appeal, less any portion previously paid. Pending determination of any appeal, the contractor may submit vouchers or invoices for charges that are not directly involved with the portion being appealed, without prejudice to the rights of either party on the appeal.
(c) Construction contracts. In the case of construction contracts, before forwarding the final payment voucher, the contracting officer shall ascertain whether there are any outstanding labor violations. If so, the contracting officer shall determine the amount to be withheld from the final payment (see subpart 22.4).
(d) Interest. The Government shall not pay interest on the amount due under a settlement agreement or a settlement by determination. The Government may, however, pay interest on a successful contractor appeal from a contracting officer's determination under the Disputes clause at 52.233-1.