Every year, King County mails property tax assessment notices to homeowners. Most people file them away and pay without a second thought. But if your home's assessed value is higher than what it would actually sell for on the open market, you may be overpaying — and you have the right to appeal.
Step 1: Understand what you are appealing
The King County Assessor sets the assessed value of your home each year. Your property tax bill is calculated by multiplying that value by the local levy rate. If the assessed value is too high, you pay too much. The appeal process lets you challenge that number before the King County Board of Equalization (BOE).
Important: you are not appealing your tax rate or your tax bill directly. You are appealing the assessed market value the Assessor assigned to your home.
Step 2: Check whether you have a case
Before filing, compare your assessed value to recent sales of similar homes in your immediate neighborhood, with similar square footage, bedroom count, condition, etc. If those homes sold for meaningfully less than your assessed value, you likely have a case.
Step 3: File your appeal before the deadline
In King County, the appeal deadline is typically July 1 of the assessment year, or 60 days after your assessment notice was mailed — whichever is later. Miss this window and you cannot appeal until the following year.
Step 4: Gather your evidence
The Board responds to one thing: market evidence. The strongest evidence is a list of comparable sales — recently sold homes near yours with similar characteristics. King County values your home as of January 1 of the assessment year, so every comparable sale needs to be adjusted — for market changes between its sale date and that valuation date, and for any differences from your home in size, condition, or other features. See what counts as a strong comparable for the specific criteria the Board looks for.
This is where most homeowners get tripped up. The burden of proof is on you — by law, the Assessor is presumed to be correct. If your comparable sales don't clearly support a lower value, the Board will side with the Assessor.
Step 5: Hearing
The BOE will schedule a hearing. Due to appeal volumes, hearings are typically scheduled 6 months or more after you file. The hearing is for the petitioner or their agent to present evidence, the Assessor may respond, and the Board makes a decision. Hearings are informal — no lawyer is required, just clear, organized evidence.
If you file with Appealo, we represent you at the hearing — walking the Board through your evidence and answering their questions on how it supports your case — so you do not have to attend.
What are the odds?
According to the Board, approximately 25% of cases that reach a hearing result in some type of reduction. The cases that win are almost always backed by solid comparable sales data. Vague arguments or appeals filed without evidence rarely succeed.
How Appealo helps
Appealo is built specifically for King County single-family and townhouse homeowners. Enter your address and we will run a comparable-sales analysis, and only recommend filing when the evidence is strong. If there isn't strong evidence to support a lower value, we tell you — filing a weak case wastes your time and ours. If you do have a case, we file on your behalf and represent you at the hearing — all for a flat $79, only if your assessed value is reduced. No commission. No percentage of savings.