951 King County homeowners took a property tax appeal all the way to a decision in 2024, and 210 of them got a reduction. That's 22.1 percent. Here's what the county's own hearing record says about your odds, what a win is worth where you live, and the one finding that should change how you file.
The typical successful homeowner appeal took $146,000 off the assessed value. And King County's 2026 levy rates run from about $8.59 to $10.58 per $1,000 of value depending on the city, so that reduction works out to roughly this much in the first year.
| City | 2026 rate per $1,000 | Saved in year one |
|---|---|---|
| Renton | $10.58 | $1,545 |
| Shoreline | $9.95 | $1,453 |
| Seattle | $9.91 | $1,447 |
| Kent | $9.45 | $1,380 |
| Bellevue | $8.59 | $1,254 |
Filing doesn't cost anything in King County. So the honest way to think about it is that roughly one in five homeowners who sees it through gets somewhere around $1,400 a year, and four in five spend their time and get nothing.
Of the 210 homeowners who won a reduction, 159 of them, about 76 percent, won because the assessor recommended the reduction rather than because the board overruled them.
Now the county's record labels those two things separately, so you can actually count them. And it changes what you should actually do, because your evidence is worth the most early, in front of the person who set your value, rather than saved up for a hearing.
First, attach your evidence when you file. Washington lets you submit it up to 21 business days before the hearing (WAC 458-14-066), and the county's own petition form recommends sending it as soon as possible, because that raises the chance of a reduction offer without a hearing at all. Next, check the box asking for the assessor's information. It's right there on the form, it doesn't cost anything, and it obliges the assessor to send you the comparable sales they're planning to rely on.
Basically the board's looking at whether the whole range of your comparable sales sits below the assessed value. So when an owner's sales run from say $830,000 to $904,000 and the county has the home at $972,000, those sales support a lower value and they don't support the assessment. That's a winning case.
But when the combined range of both sides' sales covers the assessed value as well as the owner's number, the board sustains, because nothing's been clearly disproved. Washington requires "clear, cogent and convincing" evidence to overcome the assessor's value (RCW 84.40.0301), and that's a really high bar compared to an ordinary dispute.
However, a few things lose reliably, and these are the board's own words. Comparing your assessment to a neighbor's assessment isn't admissible at all, and King County's own instructions say so plainly. Price per square foot has been called "generally not a reliable method for the valuation of single-family homes." A single comparable sale "may reflect an outlier value and, thus, cannot represent an entire market." An aging roof counts as normal maintenance rather than damage. And the size of your increase, or your tax bill itself, isn't evidence about market value.
But one thing that does work is photographs of specific defects. In a 2026 case, photos of cracked window frames led the assessor to lower the home's condition rating outright.
A petition that says only that your value is too high gets thrown out as incomplete (WAC 458-14-056). The reasons box has to say something specific about why the number doesn't reflect what the home would actually sell for.
Of those 951 house appeals, 809 were in a named city and 142 were in unincorporated King County. Seattle alone accounts for 275 of them, and Seattle homeowners won 28.7 percent of the time, which is a fair bit better than the county as a whole.
But every other city falls well short of a sample worth quoting. Bellevue had 124 decided house appeals, Kirkland 59, Sammamish 58, and it drops away from there. Publishing a win rate off fifty-odd cases would honestly just be inventing a number, so we don't. There's a Seattle page and this one, and that's what the record actually supports.
Now Cook County's a different story entirely, because it decides about 140 times as many house appeals, so every one of its 38 townships has its own measured rate.
In Washington you file by July 1 or within 60 days of the date printed on your value notice, whichever is later (RCW 84.40.038). King County uses the 60-day version, and it mails notices in neighborhood waves from about May through November, so your deadline really depends on when yours arrives rather than on one county-wide date.
And our free check reads the county's own appeal system and tells you your exact date, along with whether you've got a case at all.
The outcome figures come from the King County Board of Equalization's 2024 Clerk's Record of Hearing, a 130-page PDF published on the Board's own site. We pulled 3,471 decided rows carrying a parcel number, then looked up every parcel in King County's public parcel layer to get its property type and city, because the record prints the petitioner's mailing address rather than the property's location.
And the reasoning comes from decisions of the Washington State Board of Tax Appeals at bta.wa.gov, which we read in full. The rules are RCW 84.40.0301, RCW 84.40.038, WAC 458-14-056, WAC 458-14-066 and WAC 458-14-087. The levy rates come from the King County Assessor's 2026 rate book.
There's a fuller write-up of the method in what actually happens to King County property tax appeals. If you spot an error in any of this, please write to hello@propertytaxbuddy.com and we'll correct it and say what changed.