48 CFR §570.601

1. (a)Lease tenant agencies may need overtime services and utilities on a regular or intermittent basis. Lease contracting officers may negotiate overtime rates for services and utilities and include those rates in leases where a need is projected. Only lease contracting officers may negotiate overtime rates.
2. (b)An independent government estimate is required in support of the negotiated rate.
3. (c)Order. To order overtime services and utilities, if the order does not exceed the simplified acquisition threshold, a warranted contracting officer's representative, in GSA or the tenant agency, may place an order. The order must reference the lease number.
4. (d)Payment. Do not make final payment for services and utilities until confirmed as delivered in a satisfactory manner.