((a)) The Department of the Treasury has a working capital fund. Amounts in the fund are available for expenses of operating and maintaining common administrative services of the Department that the Secretary of the Treasury, with the approval of the Director of the Office of Management and Budget, decides may be carried out more advantageously and more economically as central services.

((b)) Amounts in the fund remain available until expended. Amounts may be appropriated to the fund.

((c)) The fund consists of—

((1)) amounts appropriated to the fund;

((2)) to the extent transferred to the fund by the Secretary, the reasonable value of supply inventories, equipment, and other assets and inventories on order for providing services out of amounts in the fund, less related liabilities and unpaid obligations;

((3)) amounts received from the sale or exchange of property; and

((4)) payments received for loss or damage to property of the fund.

((d)) The fund shall be reimbursed, or credited with advance payments, from amounts available to the Department or from other sources, for supplies and services at rates that will equal the expenses of operation, including accrual of annual leave and the depreciation of plant and equipment. Amounts the Secretary decides are in excess of the needs of the fund shall be deposited at the end of each fiscal year in the Treasury as miscellaneous receipts.