Office of Financial Management
Link to OFM website survey.

Home » Population » Annexations

Annexations and municipal boundary changes FAQ

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?

Please refer to the Annexation/Boundary Line Adjustment Documentation Checklist.

Are other documents sometimes needed?

Yes. Some annexations have unique conditions that require proof of accomplishment.

Why does OFM need a legal description?

OFM needs a legal description that can be used by Washington State Department of Transportation (WSDOT) cartography staff to plot the annexed area. The legal description needs to describe a specific area for OFM to approve for population purposes. The following actions are suggested:

What should be included in the map of the annexed area?

The map does not have to show the entire city/town—just enough to be able to locate the annexed area in geographic space. OFM's preference is for the annexed area to be outlined in red and the city/town limits prior to the annexation in green. Street names should be present and legible. The map is not the legal definition of the property annexed.

My city plans to contract for an annexation census. What do I need to know?

Under statutes RCW 35.13.260, RCW 35A.14.700, and RCW 43.62.040, the count of population and housing in annexations or other boundary changes shall be made in "accordance with practices and policies, and subject to the approval of The Office of Financial Management". Therefore, when contracting for these services, local jurisdictions should ensure that the consultant, by contract, is required to follow OFM's guidance and that their work be acceptable to OFM who must approve the results. Failure to follow the proper process could result in cities having to recount the annexed population and housing, costing additional funds. It is highly recommended that OFM be notified in advance of which contractor is hired. If the contractor has not attended an OFM census administrator training session, arrangements need to be made for training. If you have questions, please contact us at

Can you tell me more about effective dates as they relate to ordinances, annexations, and resolutions for my city?

Ordinance effective date is when the law takes effect. Annexation effective date is when the annexed area legally becomes part of the city/town. A resolution is effective upon passage by municipal council. The majority of the time, ordinance effective date and annexation effective date are the same. In some cases, the law or local planning needs dictate that they be different. Please refer to the Annexation Effective Dates document for more information.

My city is interested in annexing a large population. What do I need to know?

The legislature passed RCW 82.14.415 to encourage cities to annex high cost areas. This incentive only applies to selected cities in King, Pierce, and Snohomish Counties. The area to be annexed must be in an annexation resolution on or before January 1, 2015. RCW 82.14.415 provides tax incentives for ten years after annexation to cities annexing areas of 10,000 or more population. Cities annexing under RCW 82.14.415 are required to count population according to RCW 35.13.260 and RCW 35A.14.700. Please refer to this document for more information.

Can you tell me more about annexation filing and how it relates to revenue distribution?

The annexation filing reports to the appropriate agencies the adjusted populations to be used in the next revenue distribution cycle. The specifics of the filing/revenue distribution cycle are:

There are three separate quarterly reports in the annexation filing that can be found on our website: