38 U.S.C. § 8121

(a) The revolving supply fund established for the operation and maintenance of a supply system for the Department (including procurement of supplies, equipment, and personal services and the repair and reclamation of used, spent, or excess personal property) shall be— (1) available without fiscal year limitations for all expenses necessary for the operation and maintenance of such supply system; (2) reimbursed from appropriations for the cost of all services, equipment, and supplies furnished, at rates determined by the Secretary on the basis of estimated or actual direct cost (which may be based on the cost of recent significant purchases of the equipment or supply item involved) and indirect cost; and (3) credited with advances from appropriations for activities to which services or supplies are to be furnished, and all other receipts resulting from the operation of the fund, including property returned to the supply system when no longer required by activities to which it had been furnished, the proceeds of disposal of scrap, excess or surplus personal property of the fund, and receipts from carriers and others for loss of or damage to personal property. (b) The Secretary may authorize the Secretary of Defense to make purchases through the fund in the same manner as activities of the Department. When services, equipment, or supplies are furnished to the Secretary of Defense through the fund, the reimbursement required by paragraph (2) of subsection (a) shall be made from appropriations made to the Department of Defense, and when services or supplies are to be furnished to the Department of Defense, the fund may be credited, as provided in paragraph (3) of subsection (a), with advances from appropriations available to the Department of Defense. (c) At the end of each fiscal year, there shall be covered into the Treasury of the United States as miscellaneous receipts such amounts as the Secretary determines to be in excess of the requirements necessary for the maintenance of adequate inventory levels and for the effective financial management of the revolving supply fund. (d) An adequate system of accounts for the fund shall be maintained on the accrual method, and financial reports prepared on the basis of such accounts. An annual business type budget shall be prepared for operations under the fund. (e) The Secretary is authorized to capitalize, at fair and reasonable values as determined by the Secretary, all supplies and materials and depot stocks of equipment on hand or on order.