31 CFR § 281.7 - Limitations.
The following limitations apply to the purchase and holding of foreign exchange:
(a) Unless otherwise authorized by the Secretary, no agency or accountable officer shall purchase, or direct the purchase of, foreign exchange from any source outside the Government of the United States, except when exchange for the purpose intended is not available for purchase from within the Government.
(b) All foreign exchange acquired by agencies by transfer from the Treasury Department, without payment of dollars, for the purpose of making authorized expenditures, shall be placed with accountable officers for account of the agencies concerned.
(c) Unless otherwise authorized by the Secretary, no accountable officer shall purchase foreign exchange which, together with the balance on hand at the time of purchase, would exceed estimated requirements for a thirty-day period.
(d) To the maximum extent possible, foreign exchange accounts which are earmarked for specific programs shall be maintained on an unfunded basis. Each agency responsible for administering international agreements pertaining to the use of foreign exchange held in funded accounts shall review the agreement and other considerations relevant to each such account at least annually to determine if the account can be placed on an unfunded basis, and shall initiate appropriate action to accomplish the objective of minimizing the number of funded program accounts and the amounts therein. The resulting determinations and the status of actions undertaken shall be furnished in writing to the Treasury Department within 60 days from the date of this regulation and each time thereafter that there is a change of status of a particular account, or as requested by the Treasury Department. Exchange which becomes eligible for removal from a funded status either as a result of the foregoing determinations, or because of the expiration of the period of availability for restricted use under the terms of international agreements, or for other reasons, shall be released promptly by the program agency for transfer to a nonrestricted Treasury sales account.