Why does King County have two property tax appeal deadlines?

Official Property Value Notices mail on a staggered schedule from May through November. A single fixed date would leave late-notice owners with no time to respond. The later of July 1 and the 60-day notice window is the date that controls.

Who do I file a King County property tax appeal with?

Petitions go to the King County Board of Equalization, not the Assessor. The Assessor sets the value on the notice. The Board is the independent body that can change that value for the year under appeal.

What if I miss the King County property tax appeal deadline?

Missing both the July 1 date and the 60-day notice window usually means the 2026 assessed value stands for the year. Late relief is rare. The next Official Property Value Notice opens a new window, and a free review can still flag the home for that cycle.

King County Property Tax Appeal Deadline 2026: When to File

The King County 2026 property tax appeal deadline is July 1 or 60 days from your Official Property Value Notice mail date, whichever is later.

Bright home office desk with organized appeal folder, laptop, and phone

King County property tax appeals for 2026 must be filed with the King County Board of Equalization by July 1, 2026, or within 60 days of your Official Property Value Notice mail date, whichever is later. Most homeowners use the 60-day rolling rule.

Why does King County have two deadlines instead of one?

The King County Assessor mails Official Property Value Notices on a staggered schedule between May and November, so a single fixed date would leave owners who receive late notices no time to respond. State law lets you file by July 1 of the assessment year or within 60 days of the notice mail date, whichever comes later.

For a notice mailed September 15, 2026, the 60-day window closes November 14, 2026. The date printed on your notice is the one that matters, not the date it arrived in your mailbox.

What should you do with the deadline?

Pull your value notice and find the mail date in the upper corner. Add 60 days, then compare that to July 1, 2026, and use whichever is later. If you would rather not track this yourself, FairAppeal handles the full King County property tax appeal filing and only charges a percentage of first-year tax savings when the appeal wins. The Fair Appeal review is free, so it costs nothing to check. For the full process, see our King County property tax appeal guide, or the city guides for Seattle, Bellevue, and Kirkland.

King County

Look up if you are overpaying on your King County home.

King County reassesses every home every year and leans on neighborhood comps without seeing condition.

Frequently asked questions

When is the King County property tax appeal deadline in 2026?: King County property tax appeals for 2026 must be filed by July 1, 2026, or within 60 days of the Official Property Value Notice mail date, whichever is later. Most homeowners use the 60-day rolling rule because notices mail from May through November.
Why does King County have two property tax appeal deadlines?: Official Property Value Notices mail on a staggered schedule from May through November. A single fixed date would leave late-notice owners with no time to respond. The later of July 1 and the 60-day notice window is the date that controls.
Who do I file a King County property tax appeal with?: Petitions go to the King County Board of Equalization, not the Assessor. The Assessor sets the value on the notice. The Board is the independent body that can change that value for the year under appeal.
What if I miss the King County property tax appeal deadline?: Missing both the July 1 date and the 60-day notice window usually means the 2026 assessed value stands for the year. Late relief is rare. The next Official Property Value Notice opens a new window, and a free review can still flag the home for that cycle.