Property Tax & Ownership

How to Appeal Your Property Tax Assessed Value

A practical, step-by-step playbook for King and Snohomish County homeowners looking to contest inflated county tax assessments and lower their tax burden.

Updated for 2026 • 7 min read

Key Takeaways for Homeowners

Strict Filing Window: Appeals must be filed with the county Board of Equalization (BOE) by July 1st or within 60 days of receiving your official Value Change Notice (whichever is later).
Burden of Proof: The assessor's valuation is presumed correct by law. You must present clear, cogent, and convincing evidence (such as market sales comps) showing the assessed value exceeds true fair market value.
Focus on Comparable Sales: Your strongest evidence consists of 3 to 5 arm's-length sales of similar homes in your immediate neighborhood that occurred prior to January 1st of the assessment year.
Complimentary CMA Support: Joe Sheldon provides custom, county-ready Comparative Market Analysis reports to support your official petition submission.

1. Understanding Assessed Value vs. Fair Market Value

County assessors use mass-appraisal computer models to evaluate tens of thousands of properties simultaneously. These algorithms look at statistical neighborhood trends, square footage, and recorded sales, but they never step inside your front door.

As a result, computer algorithms frequently miss localized defects, un-updated interior finishes, structural issues, or site dis-amenities (such as heavy traffic noise or slope stability issues). In Washington State, property taxes are levied based on 100 percent of fair market value as of January 1st of the assessment year. If your county assessment exceeds what your home would have sold for on the open market on January 1st, you have grounds for an appeal.

2. The Step-by-Step Appeal Process

Step A: Review Your Official Value Change Notice

King and Snohomish Counties mail Official Property Value Change Notices between May and September. Note the postmark date immediately. You have until July 1st or 60 days from the notice date (whichever is later) to submit your formal petition.

Step B: Verify Your County Property Record Card

Look up your parcel number on the King County Assessor or Snohomish County Assessor web portal. Check for factual errors: incorrect square footage, incorrect bedroom or bathroom count, listed acreage errors, or wrong building grade classifications. Correcting factual errors is often the fastest route to a value reduction.

Step C: Gather 3 to 5 Comparable Sales (Comps)

Identify homes in your immediate sub-neighborhood that sold prior to January 1st of the assessment year. Look for properties with similar age, square footage, style, and lot size that sold for less than your assessed value. (Note: Bank foreclosures, estate sales, and forced family sales are excluded by county boards as non-arm's-length transactions).

Step D: Document Property Conditions & Defects

If your home requires significant capital repairs (such as a failing roof, cracked foundation, original electrical panel, or severe drainage issues), take clear photos and obtain written repair estimates from licensed contractors. The Board of Equalization will factor documented repair costs directly into valuation adjustments.

Step E: File Your Official Board of Equalization Petition

Submit your petition online or by mail to the appropriate county board. You do not need to submit all evidence on day one, but your initial petition form must be filed prior to the 60-day deadline. Supplemental evidence can generally be submitted up to 21 business days before your scheduled hearing date.

3. County Filing Directory & Portals

County	Appeal Board Authority	Standard Filing Window	Filing Method
King County	King County Board of Appeals / Equalization (BOE)	July 1st or 60 days from Notice Date	Online e-Appeals Portal or Paper Form eAppeals
Snohomish County	Snohomish County Board of Equalization (BOE)	July 1st or 60 days from Notice Date	Online Portal or Physical Mail Submission

Property Tax Appeal Checklist & Worksheet

Use this printable section to track your deadlines, record parcel data, and organize comparable property sales for your petition.

Parcel & Assessment Tracker

Parcel / Account #: ___________________________

Notice Date: _________________________________

Filing Deadline: ______________________________

Current Assessed Value: $______________________

Target Claimed Value: $_______________________

Process Checklist

[ ] Reviewed Official Value Change Notice

[ ] Verified Property Card Factual Accuracy

[ ] Requested Custom CMA from Joe Sheldon

[ ] Selected 3 to 5 Qualified Comps

[ ] Gathered Photo / Repair Cost Documents

[ ] Submitted BOE Petition Form Online

Comparable Sales Evidence Notes

1. Address: _________________________________________ Sale Price: $____________ Date: _________

2. Address: _________________________________________ Sale Price: $____________ Date: _________

3. Address: _________________________________________ Sale Price: $____________ Date: _________

4. Address: _________________________________________ Sale Price: $____________ Date: _________