41 CFR § 102-85.50
When does availability of funding have to be certified?
June 9, 2020
The customer agency must sign an OA prior to GSA's making any major contractual commitments associated with the space request. Typically, this should occur at the earliest possible opportunity-i.e., when funds become available. However, in no event shall certification occur later than just prior to the award of the contract to a design architect in the case of Federal construction or renovation in Federally owned space or prior to the award of a lease. This serves as a customer agency's funding commitment unless certification is provided on another document.