18 CFR § 4.304 - Payment.
(a) A payment required under this subpart must be made by check payable to the United States Treasury. The check must indicate that the payment is for ECPA Fees.
(b) If a payment required under this subpart is not made within the time period prescribed for making such payment, interest and penalty charges will be assessed. Interest and penalty charges will be computed in accordance with 31 U.S.C. 3717 and 4 CFR part 102.