Oregon Revised Statutes Commercial Transactions § 83.080

(1) At or prior to the time a retail charge agreement is made the seller shall advise the buyer in writing, on the application form or otherwise, or orally, that a service charge will be computed on the outstanding balance for each month (which need not be a calendar month) or other regular period agreed upon, the schedule or rate by which the service charge will be computed, and that the buyer may at any time pay the total unpaid balance. If this information is given orally, the seller shall, upon approval of the buyer's credit, deliver to the buyer or mail to the buyer at the address of the buyer, a memorandum setting forth this information.

(2) The seller or holder of a retail charge agreement shall promptly supply the buyer with a statement as of the end of each monthly period (which need not be a calendar month) or other regular period agreed upon, in which there is any unpaid balance thereunder, which statement shall set forth the following: