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. With the right tools, the evaluation and filing can happen in 2 days.
Appealo was built with last-minute filers in mind. We have helped King County homeowners file with less than a week before the deadline. Enter your address, get your evaluation, and if the case is strong, we handle the filing the same week.
What you need to file
- Your parcel number (on your assessment notice)
- The assessed value shown on your notice
- The value you believe is correct
- Evidence — comparable sales of similar homes in your neighborhood
Key dates at a glance
- Assessment notices mailed: typically January–April each year
- Appeal deadline: July 1, 2026 or 60 days after your notice date
- Hearing scheduled: usually 30–90 days after filing
- Board decision: typically within 30 days of hearing
Don't wait to see if the deadline is close. Check your address now — the evaluation is free and takes minutes.