Your 2027 King County property taxes are based on your home's value on January 1, 2026. To appeal that value, file with the King County Board of Equalization within 60 days of the mailing date on your notice, or by July 1 if that is later. King County mailed 2026 notices from June 18 to September 24, area by area, so some windows are still open.
Find your deadline
Type your neighborhood
Or use the date printed on your notice
Counts 60 days from the mailing date, or July 1 if later, against today's date. Confirm yours in eAppeals.
Most Seattle-area homeowners react to the February bill. By then, the appeal window closed months ago. The notice that matters is the Assessor's card that arrives in summer or fall.
The cycle
Your 2027 King County taxes were set on January 1, 2026
The Assessor values every home each year at market value: what a willing buyer would pay a willing seller. The 2026 value sets your 2027 taxes.
- Jan 1, 2026Assessor values your home at market valueThis is the date your evidence has to speak to
- Jun 18 to Sep 24Valuation notice mailed, area by areaThe mailing date on your notice starts your appeal clock
- 60 days laterLast day to file an appealMiss it and this value stands for 2027
- Mid-Feb 2027Tax statements mailedYour 2026 value times your area's 2027 levy rate
- Apr 30, 2027First half dueLate charges start May 1
- Nov 1, 2027Second half dueOctober 31 falls on a Sunday, so it moves to the next business day
A higher value doesn't mean a matching tax increase. Your bill also depends on voter-approved levies, local budgets and the total value in your area. That's why the Board looks at only one thing: your home's market value.
The deadline
The King County property tax appeal deadline is 60 days from your notice, or July 1, whichever is later
Notices go out area by area, so your deadline depends on where you live. It is 60 days from the mailing date printed on your notice, or July 1 if that is later. File online, hand deliver, or postmark by that date.
Still open as of October 16: areas mailed September 3 to 24, with deadlines from November 2 to November 23. Area names are the Assessor's. Commercial properties follow a separate schedule.
All 2026 mailing dates and deadlines
Here are the 2026 residential mailing dates from the King County Assessor, with each 60-day deadline:
| Mailed | Deadline | Areas |
|---|---|---|
| June 18 | August 17 | Algona, Pacific, Lakeland Hills |
| July 16 | September 14 | Enumclaw Plateau, City of Enumclaw, East Auburn/Southeast Kent, Cedar River/East Maple Valley |
| July 23 | September 21 | West, Central and East Shoreline, Lake Forest Park/Kenmore, Kirkland |
| July 30 | September 28 | Magnolia, Queen Anne, Capitol Hill, Madison Park/Leschi/Mt. Baker, Alki, Fauntleroy, Delridge/Georgetown/South Park, Rainier Beach, White Center/Burien, SeaTac/Tukwila, Skyway/Bryn Mawr/Downtown Renton, West Mercer Island, West Seattle, Redmond/South Woodinville/Sammamish Valley, High Point/Highland Park/Westwood, Beacon Hill, North Bend/Snoqualmie, Seward Park, NW Bellevue/Enatai/Meydenbauer/Beaux Arts, NW Renton Highlands/Kennydale, Cumberland/Kanaskat, Vashon |
| August 6 | October 5 | Central District, North and South Sammamish Plateau, Woodinville/Cottage Lake/Hollywood Hill, Inglewood/Finn Hill/Juanita, Broadview/Blue Ridge/Shilshole, Redmond Ridge, Kingsgate/Queensgate, Issaquah Highlands/Preston/Snoqualmie Ridge, East Woodinville/Bear Creek/Trilogy |
| August 13 | October 12 | Haller Lake/North Greenwood/Crown Hill, Northgate/Maple Leaf, Lake City/Matthews Beach, West and East Ballard, Columbia City/Rainier Valley, Somerset/Eastgate, East Renton Highlands, Medina/Hunts Point/Yarrow Point/Clyde Hill, Phinney Ridge/Fremont, Greenlake/Wallingford, Ravenna/University District, Laurelhurst/Windermere/View Ridge, Lake Sammamish/Redmond, Benson Hill/Panther Lake, Talbot Hill/East Kent, Newcastle, Issaquah/Lakemont, Mirrormont/Tiger Mountain/May Valley, Lake Hills, East Mercer Island |
| September 3 | November 2 | Duvall, Carnation/Fall City/Snoqualmie, Normandy Park, Maple Valley, Black Diamond/East Maple Valley, Baring/Skykomish, Lake Youngs |
| September 10 | November 9 | Bothell, Roosevelt/Wedgwood/Bryant, Burien |
| September 17 | November 16 | Bridle Trails/Wilburton/Central Bellevue, East Kirkland/Rose Hill, Sherwood/Bel-Red/SW Redmond |
| September 24 | November 23 | Steel Lake/Star Lake, West Hill Auburn, Auburn, Kentridge, Woodmont/Redondo, Twin Lakes, Federal Way, Jovita, Kent Meridian/East Hill, Lea Hill/Lake Meridian, Des Moines/SeaTac/West Kent |
Missed it? Late petitions are accepted only in very limited cases. Your next chance is next year's notice, which sets 2028 taxes.
How to appeal
How to appeal your King County assessed value, step by step
Filing is free, and most homeowners don't need an attorney. You do need evidence, because the Assessor is presumed correct. About 25% of appealed values get some reduction.
Call the Assessor first if it's a mistake. A wrong bedroom count may get fixed without an appeal. 206-296-7300.
Gather sales. Similar nearby homes that sold close to January 1, 2026 are your best evidence. Repair bids, an appraisal and photos of problems help too.
Skip what doesn't count. Your neighbor's assessment, the percent increase, your tax bill and hardship.
File. Online at eAppeals, or by mail to King County Board of Equalization, 516 Third Avenue, Room 1222, Seattle, WA 98104. One petition per parcel. No email.
Send evidence early. It's due at least 21 business days before your hearing. Hearings can take six months or more to schedule.
Join by phone, or don't. The Board can decide on the paperwork.
Watch for the decision. It's mailed within 45 days. If your value drops, you get a revised bill or a refund. Either side can appeal to the Washington State Board of Tax Appeals within 30 days.
Free help: King County's Property Tax Advisor (206-477-1060) helps with residential appeals. A broker can also pull the sales around January 1 for you.
Your record
Check your county record before you argue the value
Look up your home in King County eReal Property and compare it to the real house:
- Square footageFinished and unfinished
- Bedrooms and bathrooms
- Heat sourceLike a heat pump that replaced a furnace
- Year built and “Year Renovated”
- View, lot size and listed features
In my experience these are often out of date. Unpermitted work rarely reaches the county, and a new heat pump rarely updates the heat source.
Look before you leap. Fixing errors can raise your value, and the county can bill omitted taxes for up to three prior years. If the record undercounts your house, talk to the Assessor or a tax professional before you file.
Planning a remodel? King County offers a three-year exemption on qualifying improvements to a single-family home, but you must apply before construction is done. 206-263-2338.
If you're selling
Selling in the next year? Fix the record before buyers find it
- A sale doesn't reset the value. The buyer's first bill uses the value already on the roll. Sales feed the next January 1 value.
- A late appeal mostly helps the next owner. Taxes are prorated at closing, and appeals take months.
- Buyers and appraisers compare the record to your listing. A 2,800-square-foot listing on a 2,100-square-foot record raises permit questions. Answer them before you list, not during inspection.
A year or two out? Pull your record, gather your permits, and plan how you'll explain any gap.
FAQ
Frequently asked questions about King County property tax appeals
When are King County property taxes due in 2027?
April 30 and November 1, 2027 (October 31 falls on a Sunday). Statements mail in mid-February.
How do I find my King County assessed value?
Search your address in King County eReal Property.
Do I still pay my taxes while my appeal is pending?
Yes. If your value drops, you get a revised bill or a refund.
Does buying a house change the assessed value?
Not right away. The current year's value is already set. Your sale informs the next January 1 value.
What if the county has my square footage wrong?
Call the Assessor at 206-296-7300. Fixing an overstatement can lower your value. Fixing an understatement can raise it and bring omitted taxes for up to three prior years.
Is appealing my property taxes worth it?
Filing is free, and about 25% of appealed values get some reduction. Winning cases rest on sales near January 1.
Can I appeal after the deadline?
Only in very limited cases. Most people wait for next year's notice.
The bottom line
Your 2027 taxes rest on your January 1, 2026 value. Find the mailing date on your notice, count 60 days, check your county record, and bring sales, not frustration.
I'm a real estate broker, not a tax advisor or attorney. Confirm your deadline with the King County Board of Equalization (206-477-3400), and talk to your tax professional about your situation.
Curious what your county record means for a future sale? I'm glad to take a look with you.
Sources
- How to appeal your valuation, King County Property Tax Advisor
- How to appeal a property tax assessment, King County Board of Appeals and Equalization
- Residential notice mailing date, 2026, King County Assessor
- eAppeals, King County Board of Equalization
- Residential property taxes, King County Assessor
- Property tax FAQ, King County Treasury Operations
- eReal Property, King County Assessor