31 U.S.C. § 1515 — Authorized apportionments necessitating deficiency or supplemental appropriations

(a) An appropriation that must be apportioned under section 1512 may be apportioned in a way showing that a deficiency or supplemental appropriation is needed, but only as necessary to pay legally granted increases for civilian officers and employees, including prevailing-rate employees, and for retired and active military personnel. (b)(1) Except as subsection (a) allows, an official may make, and an executive-agency head may request, such an apportionment only when the official or agency head decides it is required because (A) a law enacted after the appropriation estimates were submitted to Congress requires spending beyond administrative control, or (B) an emergency involving human safety, property protection, or people’s immediate welfare exists and an appropriation is insufficient to pay or contribute to amounts that the law fixes for particular people or requires under legal formulas. (2) If the official making the apportionment decides it shows a need for a deficiency or supplemental appropriation, the official must immediately send Congress a detailed report of the facts. The report must be referred to when the proposed appropriation is submitted.