King County property tax: rates, assessments, and how to appeal

Last updated 2026-07-09

How does King County property tax work?

King County taxes property under Washington State law, mainly RCW Title 84, which requires that all real property be assessed at 100 percent of its true and fair market value as of January 1 each year ^[1]. The Assessor's office sets that value. Then dozens of separate taxing districts, the county itself, cities, school districts, fire districts, and others, each pass their own levies. Those levies stack up into the combined rate printed on your annual bill.

Two houses on the same block can carry very different effective rates depending on which school district line they sit behind. Mercer Island homeowners face a different combined levy than homeowners in Auburn or Enumclaw, even though all three are inside King County.

Washington has no state income tax. Property and sales taxes carry more of the load here than in most states, which is part of why King County bills shock people who move in from elsewhere. For a broader grounding in how property tax is built nationally, the property tax explained guide is a good starting point before the county-specific rules below.

One number to anchor to: the Washington State Department of Revenue reports King County's average effective property tax rate, meaning taxes paid as a share of assessed value, sits around 0.93 percent, while rates by specific levy area range from roughly 0.7 percent to over 1.3 percent depending on location ^[2]. On a $700,000 home, 0.93 percent works out to about $6,510 a year.

What is the King County property tax assessment process?

The King County Assessor revalues every parcel on an annual cycle, though not every property gets a full physical inspection every year. The county runs a mass appraisal model: appraisers study recent comparable sales in each neighborhood and apply statistical models to estimate market value for every parcel in the group ^[3]. Physical inspections rotate on roughly a six-year schedule per the Assessor's revaluation program ^[10].

Your assessment notice arrives by mail, usually between late spring and fall depending on your revaluation area. The notice shows two values: land and improvement. Both matter. Both can be wrong.

The Assessor leans on three standard appraisal approaches: sales comparison (comparing your home to recent nearby sales), cost (what it would cost to rebuild the structure minus depreciation), and income (mainly for commercial and rental property). For most single-family homes, sales comparison does the heavy lifting.

A common mistake: assuming assessed value and market value are supposed to line up. In Washington they legally are, since state law requires assessment at 100 percent of market value. If you think the Assessor has your home priced above what it would actually sell for, that gap is the core of a valid appeal. Compare your assessment to the property tax assessment framework to see where errors usually hide.

Other states do this very differently. In California, the Riverside County property tax assessment system runs on Proposition 13 and typically resets value only at sale. In Texas, Tarrant County property tax assessments update annually like King County but move through a different appeals structure. King County's yearly reassessment means your value can jump hard in a single year when the market runs hot.

What are King County property tax rates by city and area?

There is no single King County property tax rate. Your bill reflects the sum of every taxing district with jurisdiction over your parcel. Here is a realistic picture of how combined levy rates varied across the county for the 2024 tax year, based on Assessor and Department of Revenue data ^[2][3]:

Area / Levy Code	Approx. Combined Rate (per $1,000 AV)
Seattle (typical)	$8.50 - $9.80
Bellevue	$7.40 - $8.60
Redmond	$7.80 - $9.00
Auburn (KC portion)	$9.50 - $11.00
Enumclaw	$10.00 - $11.50
Mercer Island	$7.20 - $8.00
Burien	$9.20 - $10.50

These ranges exist because each city holds multiple levy codes, sorted by fire district, school district, and other overlapping lines. The King County Assessor's eReal Property portal lets you pull the exact levy code and combined rate for any parcel ^[3].

Washington caps regular property tax levies: the total of all regular (non-voter-approved) levies for state and local combined cannot exceed $5.90 per $1,000 of assessed value, though voter-approved levies stack on top of that ^[1]. School levies, library levies, and voter-approved bonds can push the total well past $10 per $1,000 in much of the county.

The practical read: if you live in a school district that just passed a big construction bond, your rate climbed. That levy is legal and you cannot appeal it. What you can appeal is the assessed value the rate gets applied to.

When are King County property taxes due and what happens if you miss the deadline?

King County property taxes come due in two installments each year ^[4]:

Installment	Due Date	Late Penalty Starts
First half	April 30	May 1 (1% per month interest)
Second half	October 31	November 1 (1% per month interest)

If April 30 or October 31 lands on a weekend or holiday, the due date rolls to the next business day. Payments postmarked by the due date count.

Missing the first-half deadline does not cost you the right to pay the second half on time. The county charges interest on the delinquent amount but treats each installment on its own. Penalties under RCW 84.56.020 add 8 percent on June 1 if the first half is still unpaid, then 3 percent more on December 1 ^[1]. Interest runs at 1 percent per month on top of that.

Properties with total bills under $50 must be paid in full by April 30. Small parcels do not get the installment option.

King County Treasury takes payment online, by mail, or in person at the King Street Center in Seattle. The county does not process credit cards directly (a third-party processor charges a convenience fee of around 2.35 percent as of 2024). Automatic payment arrangements exist if you are a senior or disabled person enrolled in certain programs, but that is a separate enrollment.

If you genuinely cannot pay and have a hardship, RCW 84.56.070 lets the county accept partial payments or payment agreements in limited cases. That takes direct contact with the Treasury division and is never guaranteed.

What exemptions and relief programs reduce King County property taxes?

Washington offers several real exemptions that cut your bill in dollars, not in name. For qualifying seniors, people with disabilities, and veterans, the savings run into the thousands per year ^[5].

Senior Citizen and Disabled Person Exemption (RCW 84.36.381) This is the biggest relief program in the county. Qualifying homeowners get a cut in assessed value and a cap on their levy rate. To qualify you must be 61 or older (or disabled), own and occupy the home as your primary residence, and have combined disposable income at or below $84,000 a year (the threshold rose effective January 1, 2024 under ESHB 1355) ^[5][9]. The reduction depends on your income tier:

Income Tier	Benefit
$0 - $30,000	Exempt from all excess levies; value frozen at 2019 level
$30,001 - $55,000	Exempt from excess levies; partial value reduction
$55,001 - $84,000	Exempt from excess levies only

Apply through the King County Assessor. There is no automatic enrollment.

Property Tax Deferral Program (RCW 84.37 and 84.38) Separate from the exemption, Washington runs a deferral program for seniors and people with disabilities. The state pays your taxes and places a lien on the property, recovered when the property sells. Income limits apply and run lower than the exemption program.

Destroyed Property Relief (RCW 84.70) If your home was damaged or destroyed by fire, flood, or similar, and the structure's value dropped, you can apply for a reduction in that year's assessment.

Current Use Programs (RCW 84.34) Agricultural land, timber land, and open space can qualify for assessment at current use value instead of market value. This mainly touches rural parcels at the county's edges, but the savings can be large for qualifying properties.

Applications for the senior/disabled exemption are due by December 31 of the year you want it to apply, though late filings are sometimes accepted at the Assessor's discretion. Do not miss this window.

For how other counties handle exemptions, the Montgomery County property tax guide covers Maryland's senior credit programs, structured differently but aimed at similar households.

How do you appeal a King County property tax assessment?

The formal appeal goes to the King County Board of Equalization (BOE), an independent quasi-judicial body separate from the Assessor's office. It hears property owner appeals and can lower, raise, or leave the Assessor's value unchanged ^[6].

The deadline to file is the later of July 1 of the assessment year or 60 days after the date the Assessor mailed your change-of-value notice ^[6]. That 60-day window matters. If your notice landed in August, you have until roughly October, not July 1. Read your notice date carefully.

Filing is free. You do not need an attorney or a contingency firm. The BOE petition (Form 64 0001) is on the BOE's website and takes about 15 minutes to fill out ^[6]. You state the value you believe is correct and your reason.

After you file, the BOE schedules a hearing, usually within several months. You present your evidence. The Assessor presents theirs. The hearing officer asks questions and issues a written decision.

What evidence wins? Comparable sales, first. Find three to six homes that sold in the six to twelve months before January 1 of the assessment year, similar to yours in size, age, condition, and location, that support a lower value. The BOE wants MLS-style data or county sale records, not Zillow estimates (though Zillow can help you spot comps to then verify).

If your home has physical problems the Assessor's model missed, photos, repair estimates, and contractor bids work well as backup. A licensed appraisal carries the most weight but costs $400 to $700 and only earns its keep when the tax savings clear that expense.

Homeowners who want to run this themselves, instead of handing a contingency firm 30 to 50 percent of their first-year savings, can use the TaxFightBack DIY appeal kit, which walks through how to pull comps, complete the BOE petition, and present at the hearing.

Lose at the BOE and the next step is the Washington State Board of Tax Appeals (BTA), then Superior Court. Most homeowners stop at the BOE. The BTA is more formal and the math shifts.

For how other states run appeals, the Loudoun County property tax guide covers Virginia's process, where the appeal body and evidence standards differ but the comparable-sales strategy is nearly identical.

What evidence do you need to win a King County property tax appeal?

At the King County BOE, the Assessor's value carries a presumption of correctness. You have to beat that presumption with actual evidence, more than a hunch that your taxes are too high ^[6].

Comparable sales are your primary weapon. The BOE wants:

• Sales that closed in the twelve months before January 1 of the assessment year (for a 2025 assessment, sales from January 1 through December 31, 2024)
• Homes within a reasonable radius (tighter in dense urban areas, wider in rural ones)
• Similar square footage, lot size, age, and condition
• Arms-length deals (no foreclosures, family transfers, or distress sales)

For each comp, note how it differs from your property and whether that difference pushes value up or down. A comp 200 square feet smaller that still sold below your assessed value is strong evidence. A comp that is newer and sold for more actually hurts you.

You can pull sales data from the King County Assessor's eReal Property portal for free ^[3]. The portal shows sale date, sale price, and basic characteristics for every recorded sale in the county. The Riverside County property tax assessment process runs a similar public sales database, which shows how standardized this evidence-gathering approach is across large counties.

Beyond comps, useful backup includes:

• A current licensed appraisal (most persuasive when the comps are close calls)
• Photos of deferred maintenance, structural defects, or conditions the field inspection missed
• Contractor repair estimates for major issues
• Proof the Assessor has the wrong property characteristics (wrong square footage, phantom bathrooms)

One underused tactic: check the Assessor's property card in the eReal portal against your actual home. Errors in recorded square footage or room counts show up more than you would think, and fixing them can drop your value with zero comparables work ^[3].

Present your evidence organized and labeled. BOE hearing officers see hundreds of cases. A clean one-page summary with your comps table, followed by the backup, beats a stack of loose printouts every time.

How does King County property tax compare to other major counties?

Putting King County in context tells you whether your burden is genuinely high or about average for a large metro county.

County	State	Avg. Effective Rate	Median Home Value (approx.)	Avg. Annual Tax
King County, WA	Washington	~0.93%	~$750,000	~$6,975
Tarrant County, TX	Texas	~2.00%	~$310,000	~$6,200
Riverside County, CA	California	~0.87%	~$480,000	~$4,176
Montgomery County, MD	Maryland	~0.99%	~$520,000	~$5,148
Loudoun County, VA	Virginia	~0.89%	~$640,000	~$5,696
DeKalb County, GA	Georgia	~1.07%	~$320,000	~$3,424

Sources: Tax Foundation, county assessor data, and US Census ACS 5-year estimates ^[7][2].

Here is the read: King County's effective rate is moderate by national standards. Bills feel heavy because of the underlying home values, which have roughly doubled since 2015 in much of the county. A 0.93 percent rate on a $750,000 assessment writes a bigger check than a 2 percent rate on a $310,000 Tarrant County home, but only by a little.

For homeowners comparing across states, the DeKalb County property tax article covers Georgia's assessment ratio system, which works nothing like Washington's 100-percent approach. The Sedgwick County property tax article covers Kansas, which uses an appraised-to-assessed ratio common across the midwest.

What is the King County property tax levy and how is it calculated?

The levy process is worth knowing because it explains why your assessed value and your tax bill can move in opposite directions.

Each taxing district sets a budget, then back-calculates the levy rate needed to collect that amount from all taxable property in the district. Washington caps most regular levies at $5.90 per $1,000 of assessed value across state and local combined, under the constitutional one-percent limit codified in RCW 84.52 ^[1]. Voter-approved levies and bond levies sit outside that cap.

Here is the counterintuitive part. If assessed values across the county rise uniformly, regular levy rates often drop, because the same budget target now spreads across a larger taxable base. RCW 84.55 limits the annual revenue increase from regular levies to the lesser of 1 percent or inflation, adjusted for new construction ^[1]. So the county cannot simply pocket the windfall from rising home prices on its regular operating levies.

Voter-approved levies skip that 1-percent limit. School construction bonds, park levies, and similar measures voters passed get added on top and can hold their rate even as values climb.

So your bill can rise because your assessed value went up faster than the county-wide average (your share of the levy base grew), or a voter-approved levy passed, or both. The Assessor sets the value. The voters and elected bodies set the levies. Appealing the assessment only touches the first cause.

The King County Budget Office publishes an annual levy summary showing each taxing district's rate and total levy amount. It is public record ^[4].

What should you do if your King County assessment increased dramatically?

A big year-over-year jump in assessed value is the most common trigger for an appeal, and it pays to work it systematically instead of emotionally.

First, check the eReal Property portal and confirm the increase is real and not a clerical slip ^[3]. Notices sometimes go to the wrong address or reflect a data entry mistake the Assessor will fix by phone without a formal appeal.

Second, check the property record for accuracy. Is the square footage right? Does it show a finished basement you do not have? An extra bathroom? These errors inflate value, and fixing them is easier than a comparables fight.

Third, pull comps for your neighborhood for the twelve months ending December 31 of the assessment year. The Assessor's portal lets you search sales by neighborhood and time period. If comparable homes sold for meaningfully less than your assessment implies, you have a real case.

A rule of thumb: if your assessed value runs more than 5 to 10 percent above what you believe the home would actually sell for, an appeal is probably worth the time. If the gap is 2 to 3 percent, the evidence burden and hearing time may not pay off unless the tax dollars are big.

Fourth, file before the deadline. The BOE deadline is firm. A petition postmarked a day late usually gets rejected unless you can show the Assessor gave you the wrong deadline in writing.

Fifth, request the Assessor's work file. Under Washington public records law (RCW 42.56), you are entitled to the appraisal data the Assessor used. Seeing their comps lets you build a targeted counter. This step alone often reveals which sales they leaned on, and whether those comps actually look like your property.

Homeowners who have run this in Texas (see the Tarrant County property tax system) often find Washington's process less adversarial, partly because the BOE is independent of the Assessor and partly because Washington does not layer informal hearings before the formal appeal the way Texas appraisal districts do.

Are there property tax payment plans or hardship options in King County?

King County Treasury does not offer a broad installment plan beyond the standard two-installment schedule. But real options exist for homeowners in trouble.

The senior/disabled exemption (covered in the exemptions section above) is the biggest relief mechanism and should be the first call for eligible homeowners. Once you enroll, the reduction carries forward automatically ^[5].

For homeowners facing a genuine inability to pay from a specific hardship, recent job loss, a medical crisis, RCW 84.56.070 lets the county treasurer accept partial payments or set up arrangements on delinquent taxes. It is not advertised and it takes direct contact with the Treasury division. There is no written guarantee of approval.

Washington's property tax deferral program (RCW 84.37 and RCW 84.38) is another route for qualifying seniors and people with disabilities. The state essentially lends you the money to pay your taxes, secured by a lien and repaid when the home sells or transfers. Income limits are stricter than the exemption program, and interest runs at a low statutory rate ^[5].

If you are behind and at risk of losing your home, King County must give a set notice period before any tax foreclosure. Under RCW 84.64, the county cannot start foreclosure until taxes have been delinquent for at least three years. That is not a reason to ignore the debt (interest compounds fast), but it does mean you have time to seek help.

The Washington State Housing Finance Commission and several nonprofit housing counseling agencies in King County offer free counseling that can help with tax delinquency alongside mortgage issues. HUD-approved housing counselors in Washington are searchable at hud.gov ^[8].

Frequently asked questions

What is the average property tax rate in King County, WA?

King County's average effective property tax rate is about 0.93 percent of assessed value, per Washington Department of Revenue data. The actual rate on your parcel depends on which taxing districts overlay your address. Rates across the county range from roughly 0.70 percent in some Bellevue levy areas to over 1.30 percent in some Auburn or Enumclaw areas with heavier school and fire levies.

When are King County property taxes due in 2025?

The first-half payment is due April 30, 2025, and the second half is due October 31, 2025. If either date lands on a weekend or holiday, the deadline moves to the next business day. Payments postmarked by the due date count. Properties with annual bills under $50 must be paid in full by April 30.

How do I appeal my King County property tax assessment?

File a petition with the King County Board of Equalization by July 1 of the assessment year or within 60 days of the date on your change-of-value notice, whichever is later. The petition form (Form 64 0001) is free and available on the BOE website. You present comparable sales evidence at a hearing. No attorney is required, and there is no filing fee.

What is the deadline to appeal a King County property tax assessment?

The deadline is the later of July 1 or 60 days from the mailing date printed on your Assessor's change-of-value notice. If your notice arrived in August, you likely have until October. Go by the notice date, not the date you received it. The BOE deadline is firm; late petitions are almost always rejected.

How does King County assess property taxes each year?

The King County Assessor uses mass appraisal, applying statistical sales analysis to comparable recent transactions in each neighborhood as of January 1 each year. Washington law requires assessment at 100 percent of true and fair market value under RCW 84.40.030. Physical inspections run on a rotating cycle of roughly six years, with annual value updates driven by sales data between inspections.

Who qualifies for a King County senior property tax exemption?

Homeowners who are 61 or older (or who have a qualifying disability), own and occupy their home as a primary residence, and have combined disposable income at or below $84,000 a year qualify under RCW 84.36.381. The 2024 income threshold increase (from $58,423 to $84,000) came from ESHB 1355. Benefits range from a levy exemption to a frozen assessed value depending on income tier.

How do I look up my King County property tax assessment online?

The King County Assessor's eReal Property portal at blue.kingcounty.com/Assessor/eRealProperty lets you search any parcel by address or parcel number. It shows current assessed value, property characteristics, levy code, recent sales history, and your tax account detail. The portal is free and needs no account.

Can I pay my King County property tax online?

Yes. King County Treasury takes online payments through its payment portal. A convenience fee applies to credit cards (about 2.35 percent charged by the third-party processor). E-check payments through the portal usually carry a lower or no convenience fee. You can also pay by mail or in person at the King Street Center in Seattle.

What happens if I miss the King County property tax deadline?

Interest runs at 1 percent per month starting the day after the due date. Under RCW 84.56.020, an added 8 percent penalty hits on June 1 if the first-half payment is still unpaid, and another 3 percent on December 1. The county can start foreclosure after three straight years of delinquency, but interest compounds quickly and the total debt grows fast.

How does King County property tax compare to Tarrant County or Riverside County?

King County's effective rate (about 0.93%) is moderate nationally. Tarrant County, TX runs roughly 2.0 percent but on much lower median values (around $310,000). Riverside County, CA runs about 0.87 percent on median values near $480,000. King County bills feel large mainly because assessed values in the greater Seattle area are among the highest in the country, not because the rate itself is unusually high.

Does Washington State have a property tax relief program beyond the senior exemption?

Yes. Washington offers a property tax deferral program under RCW 84.37 (for seniors and disabled persons) and RCW 84.38 (for those with limited income). The state pays the taxes for you, placing a lien on the property, with repayment due when the home sells. Income thresholds run stricter than the exemption program. Both programs go through the county assessor.

What if the King County Board of Equalization denies my appeal?

You can appeal the BOE decision to the Washington State Board of Tax Appeals (BTA). The BTA process is more formal, requires written submissions, and may involve a de novo evidentiary hearing. If you lose at the BTA, the next step is Superior Court. Most homeowners find the math does not support going past the BOE unless the amount at issue is substantial, typically several thousand dollars in annual savings.

How do levy rates affect my King County tax bill separately from my assessed value?

Levy rates get set by each taxing district based on budget needs, subject to state caps under RCW 84.52 and the annual revenue limit in RCW 84.55. If your assessed value rises but every other property in the district rose equally, the regular levy rate may actually drop. Your bill can still climb if voter-approved levies are added or if your value rose faster than your neighbors' average.

Sources

1. Washington State Legislature, RCW Title 84 (Property Taxes): Washington law requires assessment at 100% of true and fair market value; levy caps, revenue limits (RCW 84.55), and delinquency penalties (RCW 84.56.020) are codified in Title 84
2. Washington State Department of Revenue, Property Tax: King County average effective property tax rate and levy rate distribution data by county
3. King County Assessor, eReal Property Portal: Parcel-level assessed values, property characteristics, levy codes, and sales history for King County parcels
4. King County Treasury Operations, Property Tax Payment Information: Property tax due dates (April 30 and October 31), payment methods, and levy summary data
5. King County Assessor, Senior/Disabled Exemption and Deferral Programs: Income thresholds for senior/disabled exemption (raised to $84,000 by ESHB 1355 effective 2024) and deferral program details under RCW 84.36.381, 84.37, and 84.38
6. King County Board of Equalization, Appeal Instructions and Petition Forms: BOE petition process, filing deadline (July 1 or 60 days from notice), Form 64 0001, and the presumption of correctness standard
7. Tax Foundation, Property Taxes by County: Comparative effective property tax rates for King, Tarrant, Riverside, Montgomery, Loudoun, and DeKalb counties
8. U.S. Department of Housing and Urban Development, Find a Housing Counselor: HUD-approved housing counselors available in Washington State for homeowners facing tax delinquency or foreclosure risk
9. Washington State Legislature, ESHB 1355 (2023 Session, effective January 1, 2024): Income threshold for senior/disabled property tax exemption raised to $84,000 for combined disposable income
10. King County Assessor, Revaluation and Mass Appraisal Program: Annual revaluation cycle using mass appraisal and sales comparison methodology; physical inspections on a rotating six-year cycle