Oregon Revised Statutes Revenue and Taxation § 319.375

(1) Except as otherwise provided in ORS 319.010 to 319.430, any credit for erroneous overpayment of tax made by a dealer taken on a subsequent return or any claim for refund of tax erroneously overpaid filed by a dealer must be so taken or filed within three years after the date on which the overpayment was made to the state.

(2) Except in the case of a fraudulent report or neglect to make a report, every notice of additional tax proposed to be assessed under ORS 319.010 to 319.430 shall be served on dealers within three years from the date upon which such additional taxes become due.