19 USC 1481 - Invoice; contents

(a) In general 
All invoices of merchandise to be imported into the United States and any electronic equivalent thereof considered acceptable by the Secretary in regulations prescribed under this section shall set forth, in written, electronic, or such other form as the Secretary shall prescribe, the following:
(1) The port of entry to which the merchandise is destined;
(2) The time when, the place where, and the person by whom and the person to whom the merchandise is sold or agreed to be sold, or if to be imported otherwise than in pursuance of a purchase, the place from which shipped, the time when and the person to whom and the person by whom it is shipped;
(3) A detailed description of the merchandise, including the commercial name by which each item is known, the grade or quality, and the marks, numbers, or symbols under which sold by the seller or manufacturer in the country of exportation, together with the marks and numbers of the packages in which the merchandise is packed;
(4) The quantities in the weights and measures of the country or place from which the merchandise is shipped, or in the weights and measures of the United States;
(5) The purchase price of each item in the currency of the purchase, if the merchandise is shipped in pursuance of a purchase or an agreement to purchase;
(6) If the merchandise is shipped otherwise than in pursuance of a purchase or an agreement to purchase, the value for each item, in the currency in which the transactions are usually made, or, in the absence of such value, the price in such currency that the manufacturer, seller, shipper, or owner would have received, or was willing to receive, for such merchandise if sold in the ordinary course of trade and in the usual wholesale quantities in the country of exportation;
(7) The kind of currency, whether gold, silver, or paper;
(8) All charges upon the merchandise, itemized by name and amount when known to the seller or shipper; or all charges by name (including commissions, insurance, freight, cases, containers, coverings, and cost of packing) included in the invoice prices when the amounts for such charges are unknown to the seller or shipper;
(9) All rebates, drawbacks, and bounties, separately itemized, allowed upon the exportation of the merchandise; and
(10) Any other fact that the Secretary may by regulation require as being necessary to a proper appraisement, examination and classification of the merchandise.
(b) Shipments not purchased and not shipped by manufacturer 
If the merchandise is shipped to a person in the United States by a person other than the manufacturer, otherwise than by purchase, such person shall state on the invoice the time when, the place where, the person from whom such merchandise was purchased, and the price paid therefor in the currency of the purchase, stating whether gold, silver, or paper.
(c) Importer provision of information 
Any information required to be set forth on an invoice may alternatively be provided by any of the parties qualifying as an importer of record under section 1484 (a)(2)(B) of this title by such means, in such form or manner, and within such time as the Secretary shall by regulation prescribe.
(d) Exceptions by regulations 
The Secretary of the Treasury may by regulations provide for such exceptions from the requirements of this section as he deems advisable and may allow for the submission or electronic transmission of partial invoices, electronic equivalents of invoices, bills, or other documents or parts thereof, required under this section.