King County Assessor mailing out property valuations - some residential values are down

The King County Assessor’s office has begun the annual process of mailing property valuation notices to taxpayers. 

While the valuation process is not yet complete countywide, it is clear that upward market pressure was easing in 2025 and, in some cases, lowering residential values in neighborhoods across King County. 

“After several years of significant value increases, the residential housing market in King County is cooling. This cooling is happening in other parts of the state and the country, as well,” said Al Dams, Chief Deputy Assessor. 

“On the commercial side in King County, the high vacancy rates and corresponding value decreases in the big Seattle office towers are dramatic, but the overall commercial market remains stable.”

On the commercial side, as has been widely reported, major office buildings in the Seattle central business district have experienced declining values and rising vacancy rates. According to preliminary figures, values have receded between 5% and 20% in the downtown Seattle office buildings. 

These major office buildings, however, are only a small part of the commercial sector. Commercial values remained relatively stable over the last year, and the decline among downtown office buildings will not create an appreciable increase in property taxes for the vast majority of taxpayers across King County.

It is important to remember that voter approved levies have more impact on property tax increase than do changes in home values.

The total amount of property tax collected is derived from the budgets passed by state, county, and local governments, and by locally approved levies. The value of each property determines proportionally how much each taxpayer will pay of that total amount.

Each year, County Assessors set values on every commercial and residential property value in the state. These values – set effective as of January 1 by state law – are then applied to the next year’s tax bill. Property values are being set as of January 1, 2026, for taxes due in 2027.