Code of Federal Regulations Title 39. Postal Service § 39.3006.54 Procedure for assessing and collecting fees

(1) Where the requester has previously failed to pay within 30 days of the billing date, the Commission may require the requester to pay an advance payment of the estimated fee together with either the past due fees (plus applicable interest) or proof that the past fees were paid.

(2) When advance payment is required, the administrative time limits prescribed in 5 U.S.C. 552(a)(6) (§ 3006.43) begin only after such payment has been received.