48 C.F.R. § 1432.903
The CO may modify the timing of payment specified in paragraph (a)(1)(i) and (ii) of the clause FAR 52.232-26, Prompt Payment for Fixed-Price Architect-Engineer Contracts, and/or paragraph (a)(1)(i) and (ii) of the clause at FAR 52.232-27, Prompt Payment for Construction Contracts, as appropriate, to provide for a period shorter than 30 days (but not less than 7 days) for making contract financing payments based on geographical site location, workload, contractor ability to submit a proper request for payment, or other factors. When considering a modification to these FAR standard(s), the CO should alert the finance and program officials involved in the payment process to ensure that such shorter contract payment terms to be specified in the solicitation and resulting contract will be met. A CO determination justifying a shorter payment period must be documented in writing, and incorporated into the solicitation/contract file.
48 C.F.R. § 1432.903