Wash. Rev. Code § 19.52.032
The debtor, if a natural person, or the creditor may bring an action for declaratory judgment to establish whether a loan or forbearance contract is or was usurious, and such an action shall be considered an action on the contract for the purposes of applying the provisions of RCW 19.52.030. Such an action shall be brought against the current creditor or debtor on the contract or, if the loan or debt has been fully repaid, by the debtor against the creditor to whom the debtor was last indebted on the contract. No such an action shall be commenced after six months following the date the final payment becomes due, whether by acceleration or otherwise, nor after six months following the date the principal is fully paid, whichever first occurs. If the debtor commences such an action and fails to establish usury, and if the court finds the action was frivolously commenced, the defendant or defendants may, in the court's discretion, recover reasonable attorney's fees from the debtor.
RCW 19.52.032
Severability-Savings-1967 ex.s. c 23: See notes following RCW 19.52.005.