The single most common reason homeowners miss a valid property tax appeal is simple: they ran out of time. King County has a hard deadline, and once it passes, there is no extension.
What is the 2026 appeal deadline?
For most King County homeowners, the deadline to appeal your 2026 property tax assessment is July 1, 2026, or 60 days after your assessment notice was mailed — whichever date is later. Check the mailing date printed on your notice to confirm which deadline applies to you.
Your assessment notice is not your tax bill. It is the separate notice the Assessor mails showing the assessed value of your home. The appeal deadline is tied to that notice, not to when your taxes are due.
What happens if you miss the deadline?
Missing the deadline means you cannot appeal for the current assessment year. You will need to wait until next year's assessment is issued and start the process over. If your home is over-assessed by $50,000 and your levy rate is around 1%, that is roughly $500 in overpaid taxes you cannot recover.
Can you still file if the deadline is close?
Yes — as long as you have not missed it. Many homeowners assume they need weeks to prepare an appeal, but that is not the case.
Appealo was built with last-minute filers in mind. We file within 2 business days of you signing, as long as your deadline is at least 2 business days away. Enter your address, get your evaluation, and if the case is strong, we handle the filing right away.
What Appealo needs from you
Just your property address. We look up your parcel number, pull comparable sales in your neighborhood, and build the evidence package — you don't have to gather any of it yourself.
Appeal timeline after filing
The timeline below is set by King County's own process and appeal volume, according to King County Assessor — How to Appeal Your Valuation. Your case is decided by the King County Board of Equalization (the Board):
We monitor your case with King County throughout the process and keep you updated on any progress.
The sooner you file, the sooner this timeline starts. Check your address now — the evaluation is free and takes minutes.