King County, WA

Appeal your King County property assessment

2026 assessment cycle. Updated July 8, 2026.

File your 2026 King County appeal by July 1, 2026, or 60 days after your value notice was mailed — whichever is later. You petition the King County Board of Appeals/Equalization; the mailing date is printed on your value notice, and filing is free.

The 2026 deadline

King County mails value notices on a rolling schedule from spring into fall, so there is no single county-wide deadline. Find the mailing date printed on your value notice and count 60 days; your deadline is whichever is later: July 1, 2026, or that date.

Ignore mailers that quote one filing date for every homeowner. Each home's deadline is its own; Washington county boards flag those one-date mailers as a known scam pattern. Your value notice is the source of truth.

Where to file

File your petition with:

King County Board of Appeals/Equalization
500 Fourth Avenue, Room 510
Seattle, WA 98104-2306

King County also accepts petitions online through its eAppeals system.

How the appeal works

Washington assesses every home at 100 percent of market value as of January 1, revalued every year, with no cap on increases (RCW 84.40.030). An appeal argues the assessed value is higher than the market supports.

You petition the King County Board of Appeals/Equalization on the state Department of Revenue form, the Taxpayer Petition to the County Board of Equalization. Filing is free, and you don't need a lawyer or an agent.

After you file, the Board schedules a hearing. You can appear in person or by phone, or ask the Board to decide on your written petition and evidence. You submit your comparable-sales evidence to the Board on the schedule in your hearing notice.

What Parcel prepares

Parcel prepares the complete appeal packet for your home: the filing form filled in, comparable-property evidence, and a step-by-step guide with this deadline and filing address built in. You preview the numbers for your home before paying anything; the completed packet is a fixed $49.

Start at savewithparcel.com, or look at a sample completed packet first.

Common questions

Do all King County homeowners share one deadline?

No. Your petition is due by July 1, 2026, or 60 days after your value notice was mailed — whichever is later. The mailing date is printed on your notice.

What does it cost to file?

Nothing. There is no filing fee. Parcel's completed packet, if you want it, is a fixed $49.

What form do I use?

The statewide Taxpayer Petition to the County Board of Equalization (DOR form REV 64 0075). Parcel's packet includes it filled in for your home. King County also accepts the petition online through eAppeals.

What evidence do I need?

Sales of comparable homes around the January 1, 2026 assessment date. Parcel's packet gathers that evidence for your home so you can present it to the Board.