When is the King County property tax appeal deadline?

Under RCW 84.40.038, file the later of July 1 of the assessment year, or 30 days after the date King County mailed your Change of Value notice (up to 60 days if the county has adopted a longer limit; your notice states the deadline). Most homeowners have until July 1. A 'good cause' exception applies in limited cases like documented illness, death in the family, or military deployment.

Do I need a lawyer to appeal my King County property taxes?

No. The King County Board of Equalization hears appeals from homeowners directly. Hearings are informal and there are no formal rules of evidence. What you need is a well-documented petition citing the RCWs and a few comparable sales.

How much can I save with a King County appeal?

Depends on how over-assessed you are and the quality of your comparable sales. A 10% reduction on a $750,000 assessment at a 1.0% effective rate is about $750 per year. The reduction carries forward until the next reassessment cycle, so the savings compound.

What if King County denies my BOE appeal?

You have 30 days from the BOE's written decision to appeal to the Washington State Board of Tax Appeals (BTA) under RCW 84.08.130. Choose the Informal track (final, faster) or the Formal track (on the record, appealable to Superior Court).

What form do I use for a King County property tax appeal?

Most counties prefer their own petition form. The King County Assessor's office can provide it. The statewide DOR form REV 64 0075 is also accepted by any WA county under WAC 458-14-056.

King County · 2026 assessment year

How to appeal your King County property tax assessment

The filing deadline under RCW 84.40.038, the King County Board of Equalization process, the comparable-sales evidence the board expects, and the $49 Appeal Kit that generates the petition.

Generate my King County petition Read the process

$49 flat · 60-day money-back guarantee · Free preview before you pay

Claims Maximizer Editorial. Statute-cited, primary-source methodology. Editorial standards. Published May 14, 2026 · Puget Sound

Quick facts

BoardKing County BOE
BOE officeKing County Board of Equalization, 500 Fourth Avenue, Suite 510, Seattle, WA 98104
Phone206-477-3400
FilingOnline via kingcounty.gov/BOE, or by mail
Filing fee$0
Free comp dataKing County Parcel Viewer
Appeal kit$49 flat

Filing your King County property tax appeal

Your petition goes to the King County Board of Equalization. Under RCW 84.40.038 it is due by the later of July 1 of the assessment year or 30 days after the county mailed your Change of Value notice. A county may extend that to as long as 60 days, and your notice states the deadline that applies. If you never received a notice, the July 1 default applies.

King County has the strongest free comp data set in the state. The Parcel Viewer and eReal Property tools give you sales history, assessor record cards, and lot-level detail for every parcel. Under WAC 458-14-076, the burden of proof is on you to show the assessor's value is wrong by clear, cogent, and convincing evidence. Hearings run August through December. Written decision usually arrives 2 to 8 weeks after the hearing.

Pull your parcel record

Check the square footage, bed/bath count, year built, and condition rating the assessor has on file. Wrong physical characteristics are the fastest win at a BOE hearing.

Build the comp set

Three to five arms-length sales within 12 months prior to Jan 1, within 1 mile, within 20% of square footage, same bed/bath count, comparable condition.

File the petition

Online via kingcounty.gov/BOE, or by mail. Keep proof of the filing date; the board will not hear a petition filed after the deadline without good cause.

Prepare for the hearing

Most hearings run 15 to 30 minutes. The board decides on evidence of true and fair value as of January 1, not on whether your taxes feel too high.

What the King County Board of Equalization expects

✓A completed petition form with your requested value stated
✓Three to five comparable sales with addresses, prices, and dates
✓Dated photos of any condition or deferred-maintenance issues
✓Contractor bids or repair estimates supporting a condition argument
✓A recent appraisal or closing statement, if you have one
✓The assessor's parcel detail printout showing the characteristics you dispute

If your King County BOE appeal is denied

Step 1Request the board's written findings
Step 2Appeal to the WA Board of Tax Appeals within 30 days (RCW 84.08.130)
Step 3Choose a formal hearing for a record you can appeal further
Step 4Superior Court review under the Administrative Procedure Act

Pulling comparable sales in King County

For King County, the strongest free comp source is the King County Parcel Viewer. Cross-check with Redfin and Zillow for sale price and date confirmation. Ideal comp set: 3 to 5 arms-length sales within 12 months prior to Jan 1, within 1 mile, within 20% of square footage, same bed/bath count, comparable condition. Avoid family transfers, foreclosure sales, and REO sales.

Generate your King County appeal petition

The RCW-cited petition, a comparable-sales analysis worksheet, and a BOE hearing prep script. $49 flat. Washington-only. No subscription.

Start · $49