ORS § 523.320
In the event that an assessment is made before the total cost of the improvement is ascertained, and if it is found that the amount of the assessment is insufficient to defray the expenses of the improvement, the district board may, by motion, declare such deficit and prepare a proposed deficit assessment. The board shall set a time for a hearing of objections to such deficit assessment and shall direct the secretary to publish one notice thereof in a newspaper of general circulation in the district. After the hearing the board shall make a just and equitable deficit assessment by ordinance, which shall be entered in the lien docket as provided by ORS 523.210 to 523.380. Notices of the deficit assessment shall be published and mailed and the collection of the assessment shall be made in accordance with ORS 523.280 and 523.290.
ORS 523.320