How to Appeal Your Property Taxes in King County, WA (Seattle & Issaquah)

If you own in Seattle, Issaquah, or anywhere in King County and your assessed value looks too high, you can appeal — but Washington's system works very differently from California's, so don't apply California rules here.

Washington has no Prop 13

King County reassesses property to 100% of true and fair market value every year. There's no 2%-cap base-year value like California's Proposition 13. That cuts both ways: assessments can rise (or fall) to market each year, and your appeal is simply an argument that the Assessor's market value is too high as of the January 1 valuation date.

Where and when to appeal

You appeal to the King County Board of Equalization (BOE) — independent of the Assessor. The deadline is the one most people miss: file your petition by July 1 of the assessment year, or within 60 days of the date your value-change notice was mailed, whichever is later. Confirm the exact date on your notice; once it passes, you wait a year.

The evidence

The BOE wants comparable sales — recent, arms-length sales of similar King County homes near the January 1 valuation date, matched on location, type, size, age, condition, and features (views and lot matter a lot on the Eastside). You can also point to errors in the Assessor's record (wrong square footage, condition, or beds/baths). (How to pick comps that win.) CompFinder pulls King County comps and builds the analysis for you.

File and present

Submit the BOE petition with your evidence by the deadline, then present at a hearing if needed. Keep it factual and organized. Because WA assesses to market annually, a successful appeal lowers this year's value — and gives you a documented baseline to push back next year. For the full contrast with California, see Washington vs. California property tax appeals.