Why does my city need Office of Financial Management (OFM) approval for an annexation?

State law, RCW 35.13.260 and RCW 35A.14.700, requires that annexation certificates be approved by OFM before the population and housing in an annexed area can be used for population purposes. All annexations and boundary line adjustments must have a certificate sent to OFM even if there is no population in the area.

Which documents do I need to send to OFM?