31 U.S.C. § 1531 — Transfers of functions and activities

(a) A balance of an appropriation available and needed for a function or activity transferred or assigned by law within an executive agency or between agencies may be transferred and used (1) by the organizational unit or agency receiving the function or activity and (2) for the purpose for which the appropriation was originally available. (b) For an internal transfer or assignment, the agency head decides the amount needed, with the President’s approval. For a transfer between agencies, the President decides the amount. (c) A transferred balance is (1) credited to an applicable existing or new appropriation account; (2) merged with the account’s amount; and (3) accounted for as one amount together with the amount merged. (d) New appropriation accounts may be created to carry out (c)(1).