ORS 294.323: Budget period.

(1) A municipal corporation, by ordinance, resolution or charter, may provide that the budget and budget documents for the municipal corporation be prepared for a period of 24 months. Unless so authorized by ordinance, resolution or charter, a municipal corporation may not prepare a budget and budget documents for a period longer than one fiscal year.

      (2) When the governing body of a municipal corporation prepares a biennial budget, the governing body shall certify to the assessor for each fiscal year of the budget period the ad valorem property tax amount or rate for the ensuing fiscal year.