RCW 43.88.170: Refunds of erroneous or excessive payments.

Whenever any law which provides for the collection of fees or other payment by an agency does not authorize the refund of erroneous or excessive payments thereof, refunds may be made or authorized by the agency which collected the fees or payments of all such amounts received by the agency in consequence of error, either of fact or of law. The regulations issued by the governor pursuant to this chapter shall prescribe the procedure to be employed in making refunds.