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 60 days after the date King County mailed your Change of Value notice. 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 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.

Published May 14, 2026 Puget Sound

King County, WA Property Tax Appeal (2026): Deadline, BOE, and How to File

Q: 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).

Claim Maximizer Editorial. Statute-cited, primary-source methodology. Editorial standards.

If your King County assessed value jumped this year, you have a clear, statute-backed path to appeal it. This page walks through the King County deadline, the BOE office, the form to file, and the evidence the board expects.

Filing your King County property tax appeal

The deadline rule is set by RCW 84.40.038 and applies statewide: file the later of July 1 of the assessment year, or 60 days after the date the county mailed your Change of Value notice. If you never received a notice, the July 1 default applies.

Quick facts for King County

BOE office: King County Board of Equalization, 500 Fourth Avenue, Suite 510, Seattle, WA 98104
Phone: 206-477-3400
Filing methods: Online via kingcounty.gov/BOE, or by mail
Filing fee: $0
Free comp data: King County Parcel Viewer
Assessor: King County Assessor

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.

What the King County Board of Equalization expects

The BOE is independent from the assessor and hears appeals from homeowners directly. No attorney required. 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.

The three argument types BOEs accept:

Comparable sales (market value): 3 to 5 arms-length sales of similar properties within 12 months prior to Jan 1 of the assessment year. Adjust for differences in size, age, condition, and location. This is the most common winning argument.
Errors of fact: wrong square footage, lot size, year built, bedroom count, or condition rating in the assessor's record. Usually the fastest win.
Change in condition: the property was damaged or materially changed after the valuation date. Requires documentation.

The escalation path if your King County BOE appeal is denied

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).

Pulling comparable sales for a King County appeal

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 Claim Maximizer WA Property Tax Appeal Kit produces the RCW-cited petition, a comparable-sales analysis worksheet, and a BOE hearing prep script. $49 flat. Washington-only. No subscription.

Start My Appeal →

This page is a self-help reference, not legal advice. For commercial property, condemnation, or high-value disputes, talk to a Washington-licensed attorney or property tax consultant. Statutes cited: RCW 84.40.038, RCW 84.40.045, RCW 84.48.010, RCW 84.08.130, WAC 458-14-076, WAC 458-14-056.