ORS § 323.305
If a distributor fails to make payment for stamps when payment is due, the Department of Revenue may compute and determine from any available records and information the amount required to be paid, including interest and penalties. One or more determinations may be made of the amount due for one or for more than one purchase. In making a determination the department may offset overpayments with respect to purchases of stamps against underpayments for purchases and interest and penalties on the underpayments. The department shall give the distributor written notice of its determination in the manner required pursuant to ORS 323.403. Except in the case of fraud, every notice of a determination made under ORS 323.005 to 323.482 shall be given within three years of the due date for payment of the purchase of stamps.
ORS 323.305