Seattle and King County buyers and homeowners often need more than a basic definition of property taxes. They need to know how a bill is calculated, why one home’s taxes can differ from another’s, how those taxes affect monthly housing costs, and where to verify official details before buying or budgeting.
This guide is designed to help with those questions. The information below applies to property taxes across King County, Washington, including Seattle and surrounding cities, and points you to the local county and state sources used for assessments, tax relief, and related information.
What determines a King County property tax bill?
In general, your property tax bill is based on your home’s assessed value and the levy rates that apply in your local taxing districts. Because levies and taxing districts can differ by location, two homes in different parts of King County can have different tax bills even when their values are similar. For official property-specific details, verify the assessment and billing information through King County.
In the state of Washington, property taxes are assessed, levied and collected by individual counties as opposed to cities. So, if you buy a house anywhere in the Seattle area, you will likely pay taxes for King County, Washington.
Property taxes in Seattle and throughout King County vary by city, school district, and voter-approved levies.
For the 2026 tax year, King County property taxes total $8.4 billion, an increase of approximately $770 million or 10% from the previous year’s $7.7 billion.
The following information was adapted from the “Homeowner’s Guide to Property Taxes,” published by the Washington State Department of Revenue, along with guidance from King County.
In Washington, property taxes are calculated based on (A) the assessed value of your home and (B) the rate created by the local levies that apply to your property. The King County Assessor’s Office assesses property each year at market value, which the county describes as what a willing buyer would pay to a willing seller.
That means assessed value and market value are closely related, but they are not always the same thing a buyer might see in a current listing, an offer price, or an appraisal prepared for a mortgage. For practical planning, buyers should treat the county’s assessed value as the tax starting point and the contract price as a separate number used in the purchase transaction.
The levy side of the equation is also important. King County explains that the assessor calculates the levy rate by dividing the levy by the total value of the property in the taxing district. Because taxing districts and voter-approved levies can vary by area, tax bills can differ from one property to another across Seattle and the rest of King County.
If you are buying a home and want to estimate property taxes before making an offer, a practical approach is to review the property’s current county assessment and recent tax history, then remember that future taxes can change if the assessed value changes or if local levies change. This gives you a planning estimate for affordability and escrow rather than a guaranteed future bill.
The King County Assessor’s Office assesses these taxes annually and usually mails out tax bills during the month of February. The payment due date can vary from one year to the next, so this is something you’ll need to keep track of. The due date will be clearly stated on your tax bill.
If you have a mortgage loan on your house, your monthly payments will probably include your property taxes. If you don’t have a mortgage, you will have to pay the tax office directly.
Like most counties across the country, King County uses property taxes to fund essential services such as schools, roads, and public safety.
The state’s guide to property taxes mentioned earlier included a graph showing the percentage of taxes that goes toward different uses. Local schools use up the biggest percentage of property tax in the Seattle area and King County as a whole.
The rest of the revenue goes toward state schools, city and county offices and services, firefighters, and other uses. King County collects taxes for the state, the county, cities, and taxing districts like schools, and the county gets about 20% of your property taxes.
King County and Washington State offer several forms of property tax relief, but eligibility depends on the specific program and the homeowner’s circumstances. For most readers, the main categories to review are exemptions for seniors and persons with disabilities, along with deferral options that may be available through county-administered programs.
A good starting point is King County’s property tax exemptions for seniors and persons with disabilities. These programs are generally intended for homeowners who live in the home and may qualify based on age or disability status. King County also provides information for homeowners exploring deferral options.
Because eligibility and application requirements can change, homeowners should verify details directly with King County before relying on a general summary. You can review county guidance online, use the King County senior exemption portal, or contact the exemptions team for help at Exemptions.Assessments@kingcounty.gov or 206-296-3920. For deferrals, King County lists 206-296-7300.
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Property taxes in Seattle and throughout King County vary by city, school district, and voter-approved levies. A bill depends on both the home’s assessed value and the local levy rates that apply to that property, so one home can have a higher or lower tax bill than another even when values are similar.
In Washington, property taxes are calculated using the assessed value of the home and the levy rates that apply in the local taxing districts. King County explains that the assessor calculates the levy rate by dividing the levy by the total value of property in the taxing district.
A King County property tax bill is generally based on the property’s assessed value and the levy rates for the taxing districts where the property is located. Because levies and districts differ by location, tax bills can vary across Seattle and the rest of King County.
Not exactly. King County assesses property at market value, described as what a willing buyer would pay to a willing seller, but the assessed value is not always the same as a current listing price, contract price, or mortgage appraisal. For tax planning, the county’s assessed value is the starting point.
Homeowners can view and pay their property taxes online through the King County website. For property-specific details, verify assessment and billing information directly with King County.
Yes. King County provides online access for homeowners to view and pay property taxes. Buyers and owners who need official billing or assessment details should confirm them through King County’s property tax and assessment tools.
A practical approach is to review the property’s current county assessment and recent tax history, then remember that future taxes can change if the assessed value changes or if local levies change. This can help with affordability and escrow planning, but it is not a guaranteed future bill.
King County usually mails tax bills during February, and the due date is stated on the bill. The payment date can vary from year to year, so owners should verify the current deadline on the bill or through King County. Homeowners can also pay online through the King County website.
Often, yes. If a homeowner has a mortgage, monthly payments will probably include property taxes through escrow. If there is no mortgage, the homeowner generally pays the tax office directly.
King County and Washington State offer property tax relief programs, including exemptions for seniors and persons with disabilities, and some deferral options may also be available. Eligibility depends on the specific program and the homeowner’s circumstances, so details should be confirmed directly with King County.
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