How often does King County reassess property?

King County reassesses every taxable property once a year. That is more frequent than most Washington counties, which revalue on two, four, or six year cycles. Every King County homeowner receives a fresh Official Property Value Notice for the new assessment year.

What is mass appraisal?

Mass appraisal is the statistical approach King County uses to value hundreds of thousands of homes at once. The assessor's model weighs many variables across neighborhoods and property characteristics and produces an estimate for every parcel on the roll without visiting each home.

Why does annual reassessment create more appeal opportunities?

A new assessed value arrives every year, so homeowners have a fresh chance to catch errors annually rather than waiting three or six years. Each annual cycle also opens a new filing window, which is the built-in correction mechanism.

Can the King County model get my home's value wrong?

Yes. Mass appraisal is accurate in aggregate but can miss at the individual property level. Any given year's estimate can land too high for a specific home, which is why King County gives homeowners an annual window to challenge the value.

Why King County Reassesses Your Home Every Single Year | FairAppeal

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.

Bright home office desk with organized appeal folder, laptop, and phone

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 a statistical model to value hundreds of thousands of homes at once. The model weighs many variables across neighborhoods and property characteristics, then produces an estimate for every parcel on the roll. No appraiser walks your property.

The estimate is efficient at scale and reasonable in aggregate. It is still a model-generated figure, not a measurement. At any given cycle, individual homes can land high or low relative to what an in-person review would conclude.

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 means any given year's figure could land too high for a specific home. The annual property tax appeal window is the 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, or the city guides for Seattle and Bellevue. FairAppeal reviews King County homes each year at no cost and only charges if the appeal wins, so the Fair Appeal check is free.

King County

Look up if you are overpaying on your King County home.

King County reassesses every home every year and leans on neighborhood comps without seeing condition.