19 U.S.C. § 2074

There is established a revolving fund of $300,000 which shall be available, without fiscal year limitation exclusively for transfer to the appropriation for collecting the revenue from customs to cover obligations of the United States Customs Service arising from authorized reimbursable services, pending reimbursement from parties in interest: Provided, That amounts so transferred shall be returned to the revolving fund not later than six months after the close of the fiscal year in which transferred.