I bought my first house in Seattle last year. Six months later, King County mailed me a piece of paper telling me it was worth $306,000 more than I paid for it.
Same house. Same tired roof, same list of things I already knew I'd be fixing for years. Nothing about it changed. But according to the county, it quietly appreciated by about a third of a million dollars — because a mass-appraisal model said so.
I'm a data engineer. I stare at other people's numbers for a living, and I've built enough models to know that a number this clean — a big round jump, no explanation attached — usually means nobody looked at the actual thing. It's an estimate from a computer that has never once stood in my kitchen.
Which is annoying, because a mass-appraisal model can't see condition at all. Not a tired roof, not deferred maintenance — and definitely not the things that quietly gut a home's value: a lot on a brutal slope, no ground-level way in, a rail line running past the back fence. None of that shows up in a spreadsheet of square footage.
My honest first reaction was: who is going to pay that, and why is it me? And to be clear, I love this city. Genuinely. I also write a very large check every year to fund a government whose results are, let's say, not always visible from my front porch. You're allowed to love a place and be furious about how it's run at the same time. Both things can be true. What I'm not willing to do is overpay on a number nobody can defend, just because contesting it sounds like a hassle.
So I stopped being mad long enough to go read the rules. Then I got mad again, but productively this time, and I appealed.
Turns out it's less of a hassle than you'd think — and the whole system is more gameable-in-your-favor than it looks, once you understand it. So I wrote it all down. Read in order, or jump to what you need:
- How King County property taxes actually work — why your bill can go up when values go down
- Where your money actually goes — who's getting it (spoiler: mostly schools)
- Assessed vs. market value — the gap that makes an appeal possible
- How to appeal, step by step — exactly what I did
- Ways to lower the burden — beyond a single appeal
My hearing is July 13. I'll update the appeal post with how it went, numbers and all.