Washington
State Regulations
Wash. Rev. Code §19.52.130
(1) Nothing contained in this chapter shall be deemed to limit any charge made by an assignee of a retail installment contract or charge agreement to the seller-assignor upon the sale, transfer, assignment, or discount of the contract or agreement, notwithstanding retention by the assignee of recourse rights and notwithstanding duties retained by the assignee to service delinquencies, perform service or warranty agreements regarding the property which is the subject matter of the assigned or discounted contracts or charge agreements, or to do or perform any other duty with respect to the account or contract assigned or the subject matter of such account or contract.
(2) No agreement between a credit card issuing bank and retailer shall prohibit the retailer from granting general discounts for the payment of cash, not in excess of the percentage allowed by Regulation Z, the Federal Truth in Lending Act.