7 U.S.C. § 618: Existing contracts; imposition of tax on vendee; collection

If (1) any processor, jobber, or wholesaler has, prior to the date a tax with respect to any commodity is first imposed under this chapter, made a bona fide contract of sale for delivery on or after such date, of any article processed wholly or in chief value from such commodity, and if (2) such contract does not permit the addition to the amount to be paid thereunder of the whole of such tax, then (unless the contract prohibits such addition) the vendee shall pay so much of the tax as is not permitted to be added to the contract price. Taxes payable by the vendee shall be paid to the vendor at the time the sale is consummated and shall be collected and paid to the United States by the vendor in the same manner as other taxes under this chapter. In case of failure or refusal by the vendee to pay such taxes to the vendor, the vendor shall report the facts to the Commissioner of Internal Revenue who shall cause collections of such taxes to be made from the vendee.