Oregon Revised Statutes Cities § 222.180

(1) The annexation shall be complete from the date of filing with the Secretary of State of the annexation records as provided in ORS 222.177 and 222.900. Thereafter the annexed territory shall be and remain a part of the city to which it is annexed. The date of such filing shall be the effective date of annexation.

(2) For annexation proceedings initiated by a city, the city may specify an effective date that is later than the date specified in subsection (1) of this section. If a later date is specified under this subsection, that effective date shall not be later than 10 years after the date of a proclamation of annexation described in ORS 222.177.