48 C.F.R. § 232.501-3
(b) The contracting officer may approve progress payments when the contract price exceeds the funds obligated under the contract, provided the contract limits the Government's liability to the lesser of—
[56 FR 36409, July 31, 1991, as amended at 65 FR 39722, June 27, 2000; 70 FR 75413, Dec. 20, 2005]