ORS § 319.200
If any dealer, except one subject to ORS 319.090, fails to file the report required by ORS 319.190, the Department of Transportation shall proceed forthwith to determine from the best available source the amount of motor vehicle fuel sold, distributed or used by such dealer for the period unreported, and such determination shall be prima facie evidence of the amount of such fuel sold, distributed or used. The department immediately shall assess the license tax in the amount so determined, adding thereto a penalty of 10 percent for failure to report. The penalty shall be cumulative of other penalties provided in ORS 319.010 to 319.430 and 319.990. In any suit brought to enforce the rights of the state under this section, the certificate of the department showing the amount of taxes, penalties, interest and costs unpaid by any dealer and that the same are due and unpaid to the state is prima facie evidence of the facts as shown.
ORS 319.200