Oregon Revised Statutes Public Financial Administration § 294.333

(1) A municipal corporation shall record its revenues and expenditures, on a fund by fund basis, using the cash basis, the modified accrual basis or the accrual basis of accounting, at the discretion of the municipal corporation.

(2) The basis of accounting used by a municipal corporation must be used in the current year or period and in each succeeding year or period until the basis is changed in a subsequent budget.

(3) A change in a municipal corporation's basis of accounting must be published as required under ORS 294.438.