King County revalues every home each year. Here is how the annual reassessment works, why it matters, and what it means for your 2026 assessed value.
King County reassesses every home it taxes once a year. Most Washington counties revalue every two, four, or six years. King County is one of the few counties on an annual cycle, so the number on your 2026 notice reflects what the model thinks changed in the last twelve months.
How does the King County annual reassessment actually work?
King County uses mass appraisal, a statistical model that values hundreds of thousands of homes at once. The model groups properties into neighborhoods, pulls recent sales inside each area, and applies the pattern to every parcel on the roll. No appraiser walks your property.
Your assessed value is an estimate generated from comparable sales the model treated as representative of your block. That is efficient at scale and reasonable in aggregate. It also means the figure on your notice is a prediction, not a measurement. When the sales feeding a neighborhood are skewed by a remodel or a teardown, every house in that cluster inherits the distortion.
What does this mean for King County homeowners?
An annual cycle gives homeowners more chances to catch an error than a triennial system does, since a new assessed value lands in the mailbox every year. It also gives the model more chances to overshoot your specific block. A single oversized sale can pull a whole cluster of values upward for the next cycle, and the property tax appeal window that follows is the only built-in correction.
If the 2026 figure feels high for your street, the assessment is worth a second look. For filing window and process details, see our King County property tax appeal guide. Fair Appeal reviews King County homes each year at no cost and only charges if the appeal wins.