Check the assessment year before filing
Last checked September 23, 2026 against the official sources linked below. This guide covers filings during 2026; the assessment roll or resulting tax bill may belong to a later year. Check the current official notice before filing.
September 16 notices: file by November 16 at 5 p.m.
The county mailed its 2026 value notices on September 16 and publishes Monday, November 16, 2026 at 5 p.m. as the deadline, unless the notice states otherwise. Include a copy of the notice front with the petition. Each tax parcel needs a separate petition.
A pending older appeal does not automatically challenge a newer assessment. Review each year's value and filing requirements separately, even if the property itself has not changed.
Allow time for paper filing
Thurston requires a handwritten signature, not a name typed in a script font. For 2026 it does not accept online or emailed petitions. Submit paper copies to the Board's Olympia office or drop box, or use the delivery methods in the current instructions.
For USPS filing, the county requires a postmark by 5 p.m. on the deadline date. Olympia mail is processed in Tacoma, so mailing on the final afternoon can produce a late postmark. Keep a complete copy and proof of timely filing.
Compare the property, not just the city name
An Olympia address can describe an in-town home, waterfront influence or a larger rural site. Lacey and Tumwater comparisons can also differ in age, construction quality and lot utility. Begin with the subject's actual competitive market and explain why each sale belongs in it.
Put documented record errors first. If the assessor includes finished space that is unfinished, show the discrepancy with measurements and photographs. For condition problems, connect the repair evidence to what a buyer would pay at the assessment date.
Plan for a decision after filing season
Thurston's Board reports a backlog. Ask about current scheduling before expecting a quick outcome, and keep the file organized while waiting. Filing in 2026 does not promise a decision or savings during 2026.
Maintain current contact details with the Board, monitor hearing correspondence and continue handling tax payments on their normal schedule. The value case still needs evidence even if an earlier year's appeal succeeded.
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