Washington taxes your home at full market value, so a win goes straight to your bill.
We check individual addresses here. We pulled 20 real King County homes and every single one is taxed on exactly its market value, to the dollar. There’s no cap in between. A 10 percent reduction on a $700,000 home is worth about $675 in the first year. 22 percent of homeowners who took an appeal to a decision in 2024 won a reduction.
So Washington decides these on market value, which means the evidence is recent sales of genuinely comparable homes. What matters is whether that whole set of sales sits below your assessed value. If those sales bracket your assessment rather than falling under it, boards generally sustain the assessor, because nothing's been clearly disproved.
Now a few things lose almost everywhere. Comparing your assessment to a neighbor's assessment usually isn't admissible where the argument is market value. One sale on its own can be dismissed as an outlier. And the size of your increase, or the size of your bill, isn't evidence about what your home is worth.
July 1 or 60 days from the date on your value notice, whichever is later. King County mails in neighborhood waves from May through November.
Miss it and you generally wait a year, so honestly the date matters more than the paperwork does.
And wherever you are, the single most useful thing you can do today is go find your assessment notice and read the date printed on it. That's what starts your clock, it's usually a much shorter window than people expect, and there's no getting it back once it's gone.
So type your address into our free check and we'll read the county's own records, work out whether the evidence actually supports an appeal, and tell you straight. Most people who use it get told not to bother, which is the point.
Check your Washington home, free
Also, there's one move that has nothing to do with appealing and that a lot of people miss entirely. Most states take exemptions off your bill before any of the value arithmetic happens, starting with a homestead exemption if you actually live in the house, and usually extra ones for owners over 65, for veterans, and for people with disabilities. They're often worth more than an appeal win, they carry forward year after year rather than needing to be re-won, and plenty of people who qualify have never filed for them. Your county assessor's website lists what's available where you live, and it costs nothing to look.
We screened all fifty states and DC on the same two questions. Does winning a lower market value actually lower your bill, or is there a cap sitting in between? And can the evidence even be assembled from public records?
This comes from our own fifty-state screen, which checked each state's cap structure, whether sale prices are public, whether an assessment-based argument exists, and how many appeals actually get filed. Where we quote an appeal count it came from the state or county that published it. If you spot an error, please write to hello@propertytaxbuddy.com and we'll correct it and say what changed.