2 U.S.C. § 6503: Payments from Senate contingent fund

No payment shall be made from the contingent fund of the Senate unless sanctioned by the Committee on Rules and Administration of the Senate. Payments made upon vouchers or abstracts of disbursements of salaries approved by said Committee shall be deemed, held, and taken, and are declared to be conclusive upon all the departments and officers of the Government: Provided, That no payment shall be made from said contingent fund as additional salary or compensation to any officer or employee of the Senate.