King County property tax appeal 2027: deadline, forms and how to file
To appeal your 2027 King County assessment, file with the King County Board of Appeals and Equalization by 1 Jul 2027, online at blue.kingcounty.gov or by mail.
Protest deadline1 Jul 2027· 254 days leftThe Assessor mails valuation change notices each year between May and November of the assessment year.
Data as of 20 Oct 2026 · King County Board of Appeals and Equalization (the county Board of Equalization; independent of the assessor)Check your own assessment
Free. We compare the value on your notice with recent sales of similar homes nearby and tell you whether an appeal is worth filing. Have your assessment notice and tax bill handy.
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How to file in King County
- Step 1 · by 1 Jul 2027
File the appeal
Online at blue.kingcounty.gov with the account number on your notice, or by mailing Form 64 0075. State the grounds the county recognises.
- Step 2 · before the hearing
Prepare and submit your evidence
The assessor’s value is presumed correct; you need specific market evidence that it is wrong (WAC 458-14-046). “Taxes are too high” or a large percentage increase is not enough. Use comparable sales from the last five years, adjusted to January 1 (sales closest to that date count most), a recent appraisal, photos and repair estimates (WAC 458-14-087). Ask the assessor for the comparable sales it used; it must provide them at least 21 business days before your hearing, and new evidence from either side is due 21 business days before it (WAC 458-14-066).
- Step 3
Meet, then hear
An talk to the assessor with County Assessor comes first; if you decline the offer, the King County Board of Appeals and Equalization hears the case. Most reductions happen at the first step.
Before you file: how to read your notice · evidence that works · informal vs formal hearing · when not to appeal
Forms
| Form | Number | Use | Format |
|---|---|---|---|
| Taxpayer Petition to the County Board of Equalization for Review of Real Property Valuation Determination | 64 0075 | The statewide petition. Give your opinion of value and the market evidence behind it; attach the notice if you file after July 1. | |
| Informal Property Tax Appeal (Board of Tax Appeals) | — | Only if you appeal the county board’s decision to the State Board of Tax Appeals. Attach the board’s order. | |
| Real Property Petition to the King County Board of Appeals and Equalization (2026 form) | — | Paper petition for single-family homes, vacant land, commercial real estate; the 2027 edition is not yet posted | |
| eAppeals Online Real Property Petition | — | Online petition filing and filing-date lookup by parcel or address | Online |
| Authorization of Agent | — | Designate a representative for the appeal | |
| Waiver of Filing Deadline (late filing instructions) | — | Request to accept a late petition for a lawful good-cause reason |
Appeal levels
| Level | Who hears it | Deadline | Cost |
|---|---|---|---|
| Talk to the assessor | County Assessor | Any time; it does not extend the petition deadline | Free |
| Board of Equalization | King County Board of Appeals and Equalization (the county Board of Equalization; independent of the assessor) | July 1, or 30–60 days after the notice, whichever is later | Free |
| Board of Tax Appeals | Washington State Board of Tax Appeals | 30 days after the county board’s decision is mailed | Free |
What evidence the board accepts
The assessor’s value is presumed correct; you need specific market evidence that it is wrong (WAC 458-14-046). “Taxes are too high” or a large percentage increase is not enough. Use comparable sales from the last five years, adjusted to January 1 (sales closest to that date count most), a recent appraisal, photos and repair estimates (WAC 458-14-087). Ask the assessor for the comparable sales it used; it must provide them at least 21 business days before your hearing, and new evidence from either side is due 21 business days before it (WAC 458-14-066).
King County questions
When is the King County appeal deadline for 2027?
No earlier than July 1, 2027. The rule: July 1 of the assessment year or within 60 days of the mailing date on the value notice or other determination, whichever is later (King County has adopted the 60-day period). If your notice was mailed late in the year, the deadline printed on it controls.
How do I appeal my assessment in King County?
File online at blue.kingcounty.gov, or send petition Form 64 0075 to the King County Board of Appeals and Equalization (the county Board of Equalization; independent of the assessor), King County Board of Equalization, 516 Third Avenue, Room 1222, Seattle, WA 98104.
What evidence does the board accept?
Market evidence: comparable sales from the last five years adjusted to January 1, a recent appraisal, photos and repair estimates. The assessor’s value is presumed correct, and saying taxes are too high is not grounds for a change.
Can I see the assessor’s comparable sales?
Yes. Ask the assessor; it must give you the sales and valuation data it used at least 21 business days before your hearing (WAC 458-14-066). Your own new evidence is due by the same point.
How do I contact the King County Department of Assessments (Assessor's Office)?
Mail: King County Board of Equalization, 516 Third Avenue, Room 1222, Seattle, WA 98104. Phone: 206-477-3400. Hours and walk-in details: kingcounty.gov.
What if I disagree with the board’s decision?
Appeal to the State Board of Tax Appeals within 30 days after the board’s decision is mailed. There is no filing fee, and late appeals are dismissed.
Check whether yours is over-assessed
Nearby counties
Pierce County · Snohomish County · Kitsap County · Kittitas County · Island County · Thurston County · Chelan County
- King County: Appealing a valuation
- King County: How to appeal your valuation
- King County: File your appeal by mail
- King County Board of Appeals and Equalization
- King County BOE: How to appeal a property tax assessment
- King County BOE: Property tax assessment appeals forms
- King County BOE eAppeals
- RCW 84.40.038 — Petition to the county board of equalization
- RCW 84.40.045 — Notice of change in valuation
- WAC 458-14-066 — Exchange of valuation information
- WAC 458-14-087 — Evidence of value
- RCW 84.08.130 — Appeals to the Board of Tax Appeals
- Washington DOR — Appeal my property assessment
- Board of Tax Appeals — Residential property appeals
- needs_verification: deadlineRule: the Assessor 'how to appeal' page says 'July 1 or no later than 60 days after you receive your property value notice' while the mail page and petition form say 60 days from the mailing date on the notice; the mailing-date wording (also in the 2025 petition form) is used here.
- U.S. Census Bureau, county population estimates (2024) and county gazetteer (2024).