41 U.S. Code § 4307. Contractor certification
(a) Content and Form.—
A proposal for settlement of indirect costs applicable to a covered contract shall include a certification by an official of the contractor that, to the best of the certifying official’s knowledge and belief, all indirect costs included in the proposal are allowable. The certification shall be in a form prescribed in the Federal Acquisition Regulation.
(b) Waiver.—An executive agency may, in an exceptional case, waive the requirement for certification under subsection (a) in the case of a contract if the agency—
determines that it would be in the interest of the Federal Government to waive the certification; and