19 CFR § 143.27
Invoices
July 16, 2020
In the case of merchandise imported pursuant to a purchase or agreement to purchase, or intended for sale and entered informally, the importer shall produce the commercial invoice covering the transaction or, in the absence thereof, an itemized statement of value.
[T.D. 85-39, 50 FR 9612, Mar. 11, 1985]