37 U.S.C. § 456 — Managed travel program refunds

(a) Credit of Refunds: The Secretary of Defense may credit refunds tied to Department of Defense managed travel programs — refunds that come directly from official travel^* — to certain accounts. Those accounts are the Department's operation-and-maintenance accounts or its research, development, test, and evaluation accounts, whichever the Secretary designates, as long as the accounts are available for obligation in the fiscal year the refund is collected.

(b) Use of Refunds: Refunds credited this way may only be used for two things: official travel, or improving the efficiency and financial management of official travel.

(c) Definitions:
(1) "Managed travel program" includes air travel, rental cars, trains, buses, dining, lodging, and travel management. It does NOT include rebates or refunds from using the Government travel card, the Government Purchase Card, or travel arranged through Government Contracted Travel Management Centers.
(2) "Refund" includes miscellaneous receipts credited to the Department and identified as a refund, rebate, repayment, or similar collected amount.