31 U.S.C. § 1535 — Agency agreements

(a) An agency head or major unit may order goods or services from a major unit in the same or another agency if money is available; the order is in the Government’s best interest; the supplying unit can provide or contract for them; and the ordering agency head decides a commercial enterprise could not provide them by contract as conveniently or cheaply. (b) On the supplying unit’s written request, payment must be made promptly by check. It may be paid in advance or when the goods or services are provided, for any estimated or actual amount the supplying unit determines. The bill or payment request need not be audited or certified before payment. Advance payments must later be adjusted as the agency heads agree, based on actual cost. (c) Procurement conditions or limits applying to the ordering agency’s money also apply to the order or contract. (d) The order or agreement obligates the ordering agency’s appropriation. That obligation is reduced to the extent the supplying unit, before the appropriation’s availability ends, has not incurred obligations for providing the goods or services or making an authorized contract with someone else to provide them. (e) This section does not authorize orders for goods or services provided by convict labor and does not change other laws about working funds.