15 U.S.C. § 1666f — Inducements to cardholders by sellers of cash discounts for payments by cash, check or similar means; finance charge for sales transactions involving cash discounts

With respect to credit^* 1 card which may be used for extensions of credit in sales transactions in which the seller is a person^* other than the card issuer^*, the card issuer may not, by contract or otherwise, prohibit any such seller from offering a discount to a cardholder^* to induce the cardholder to pay by cash, check, or similar means rather than use a credit card^*.

With respect to any sales transaction, any discount from the regular price offered by the seller for the purpose of inducing payment by cash, checks, or other means not involving the use of an open-end credit plan or a credit card shall not constitute a finance charge as determined under section 1605 of this title if such discount is offered to all prospective buyers and its availability is disclosed clearly and conspicuously.