31 USC 1324 - Refund of internal revenue collections
(a) Necessary amounts are appropriated to the Secretary of the Treasury for refunding internal revenue collections as provided by law, including payment of
(1) claims for prior fiscal years; and
(2) accounts arising under
(A) Allowance or drawback (Internal Revenue);
(B) Redemption of stamps (Internal Revenue);
(C) Refunding legacy taxes, Act of March 30, 1928;
(D) Repayment of taxes on distilled spirits destroyed by casualty; and
(E) Refunds and payments of processing and related taxes.
(b) Disbursements may be made from the appropriation made by this section only for
(1) refunds to the limit of liability of an individual tax account; and