Cash received by the Attorney General as security on an immigration bond shall be deposited in the Treasury of the United States in trust for the obligor on the bond, and shall bear interest payable at a rate determined by the Secretary of the Treasury, except that in no case shall the interest rate exceed 3 per centum per annum. Such interest shall accrue from date of deposit occurring after April 27, 1966
, to and including date of withdrawal or date of breach of the immigration bond, whichever occurs first:
That cash received by the Attorney General as security on an immigration bond, and deposited by him in the postal savings system prior to discontinuance of the system, shall accrue interest as provided in this section from the date such cash ceased to accrue interest under the system. Appropriations to the Treasury Department for interest on uninvested funds shall be available for payment of said interest.