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
Sales within the past 12 months carry the most weight. The Board views older sales as less reliable evidence of current market value. In a volatile market, sales from 18 months ago may be dismissed entirely.
Proximity
Homes within 0.5 to 1 mile of your address in the same neighborhood are strongest. Cross-city comparables — using a Renton sale to challenge a Bellevue assessment — will be questioned unless the properties are genuinely similar in every other way.
Physical similarity
The comparable home should be similar in square footage (within 15–20%), bedroom and bathroom count, lot size, and age. A 1,400 sq ft rambler is not a strong comparable for a 2,800 sq ft two-story home, even if they are on the same street.
Condition
A fully renovated home that sold for $950,000 is not a useful comparable for your unrenovated home assessed at $1,050,000. The Board will note the difference in condition and 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
- Distressed sales (foreclosures, estate sales at below-market prices)
How many comparables do you need?
There is no minimum, but three to five strong comparables give the Board 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.
Appealo focuses exclusively on single-family homes in King County. Our comparable analysis searches recent SFH sales 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.