The King County Board of Equalization is not a complaints department. Arguing that your taxes feel too high, or that your neighbor pays less, will not move them. What moves the Board is comparable sales evidence — recently sold homes that demonstrate your home's fair market value is lower than the Assessor's figure.
Why comparables are the only argument that works
By law, the Assessor is presumed to be correct. The burden is entirely on you to prove otherwise. The Board's standard is market value — what a willing buyer would pay a willing seller, with neither under pressure. Comparable sales of similar homes are the most direct evidence of that.
What makes a strong comparable
Recency
King County values every property 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.
Proximity
Comparables should share your home's county-defined neighborhood area and zoning — not just a nearby mile radius. Comps from outside that boundary, like using a Renton sale to challenge a Bellevue assessment, will be questioned.
Physical similarity
The comparable home's physical features — square footage, lot size, age, and others — should be similar to yours, or adjusted for the differences. Two homes that differ significantly in size or type aren't strong comparables, even if they're on the same street.
Condition
The comparable's condition should be similar to yours, or adjusted for the difference. A fully renovated home isn't a useful comparable for an unrenovated one unless that gap is accounted for — otherwise the Board will discount the comparable accordingly.
What the Board will dismiss
- Zillow estimates — not considered market evidence
- Your purchase price from several years ago — only useful if recent
- A neighbor's lower assessment — assessments are set individually, not comparatively
- Sales of condos or townhomes — not comparable to single-family homes
- Non-arm's-length sales — a parent selling a home to their child, a foreclosure, or any other sale not conducted at market value
How many comparables do you need?
There's no set range, but three to five strong comparables are usually enough to establish a pattern. One outlier sale is easy to dismiss. Three sales that all point to the same lower value is much harder to argue against. More isn't automatically better, either — padding the case with weak or borderline comps just gives the Assessor more openings to pick apart.
Appealo focuses on single-family homes and townhouses in King County. Our comparable analysis searches recent sales of similar properties near your address, scores each one for similarity, and surfaces the strongest evidence for your case.
What if there are no good comparables?
Sometimes a neighborhood simply hasn't had many sales, or the sales that did happen were at prices above your assessed value. In that case, the honest answer is that you probably don't have a strong appeal. Filing anyway — without solid comparables — is unlikely to succeed and wastes your time. This is exactly the scenario where an honest preliminary evaluation saves you from a futile process.