19 C.F.R. § 24.34 – Vouchers; vendors' bills of sale; invoices.

(a) Vouchers or invoices for transportation and related services which are intended for payment from official funds shall contain the following certification signed by the claimant:
I certify that the above bill is correct and just and that payment has not been received.
Vouchers, vendors' bills of sale, or invoices for purchases or services other than personal do not require the foregoing certification.
(b) Every voucher shall be in the name of the person or persons furnishing the service or supplies, except in the case of a service or supplies paid for in an emergency by a Customs officer or employee, in which case the voucher may be in the name of the officer or employee who made the payment.
(c) The signature of a claimant made by a mark shall be attested in each case by a disinterested witness.
(d) The dates appearing on vouchers and on receipts filed in support thereof shall always be the actual dates of the transactions recorded or action taken thereon. As many copies in memorandum form, duly authenticated if desired, may be prepared as administrative or other requirements demand.
(e) When an erasure, interlineation, or change of any kind is made in a voucher after it has been certified by the claimant, such correction or change shall be initialed and dated by the claimant.
(f)
1. (1) Vouchers for passenger transportation furnished Customs officers or employees on Government transportation requests, standard Form 1169, and vouchers for transportation of freight and express furnished on Government bills of lading, standard Form 1103, issued by Customs officers or employees shall be rendered on Public Voucher for Transportation Charges, standard Form 1171 or 1113, respectively, to the Customs office to be billed as indicated on the transportation request or bill of lading.
2. (2) Charges for freight or express must not be included on the same vouchers with charges for passenger transportation. The words “Passenger,” “Freight,” or “Express,” as the case may be, should be printed or otherwise placed by the carrier immediately above the title of the voucher form. Original Government bills of lading, standard Form 1103, or transportation requests, standard Form 1169, or certificates in lieu thereof, standard Forms 1108 or 1172, respectively, shall be attached to these vouchers.