King County Property Tax: Pay, Search, Due Dates & Relief
King County property tax is split between different county functions. The King County Assessor handles valuation, property records and several relief programs, while King County Treasury Operations handles tax bills, payments, receipts, refunds and delinquent accounts.
The safest path is to find the correct parcel or tax account first, confirm the 2026 bill and installment, check whether a mortgage servicer already paid, then use the official county system for payment, tax relief, deferral or an assessment appeal.
Quick Answer: What Should You Do First?
Find the tax account number or parcel number, match it to the property address, then review the current King County tax account before paying. The county says the number can be found on the property-tax statement or Assessor’s Valuation Change Notice, and real-property information can also be located through eReal Property or Parcel Viewer.
Use Treasury Operations for the live balance, payment, receipt, refund and delinquency questions. Use the Assessor for valuation, property characteristics, tax-relief programs and assessment information.
Do not pay from an old screenshot, lender estimate or prior statement. Use the live King County account because payment, delinquency and escrow status can change.
Which King County Office Handles Your Problem?
Use for assessed value, property characteristics, valuation notices, exemptions, deferrals and property-record questions.
Use for tax bills, online payments, mailed payments, account balances, receipts, refunds and delinquent taxes.
Use for a formal assessment appeal after reviewing the valuation and filing deadline.
Provides taxpayer assistance with property-tax matters, including understanding assessment appeal options.
Use when delinquent taxes have reached a foreclosure-related stage. Current payoff costs can differ from an ordinary late balance.
Business personal property and some mobile-home accounts use different identifiers and payment procedures from ordinary real property.
If the problem is “my property is valued too high,” calling Treasury will not fix the assessment. If the problem is “my payment did not post,” the Assessor is not the payment office.
How to Search King County Property Tax Records
King County gives property owners more than one search route. Use the tool that matches what you already know.
Use the account number from the property-tax statement or valuation notice when you are ready to view the tax bill or make a payment.
Useful for Assessor records, mapping, assessment information, levy details and property research.
Use Parcel Viewer or another official property-information tool to find the correct parcel before opening the payment account.
King County’s GIS Parcel Viewer supports address, parcel-number and condo-name searches and links selected parcels to Assessor information.
- Open King County Parcel Viewer or the Assessor property-information page.
- Search by address or parcel number.
- Confirm the correct parcel and property address.
- Copy the parcel or tax account number carefully.
- Open the official property-tax payment system.
- Confirm the tax year and live amount before paying.
Owner name is useful for research but can be outdated, abbreviated or show a trust. Match the parcel and address before paying.
How to Pay King County Property Tax Safely
- Open the official payment page.
- Search using the tax account or parcel number.
- Confirm property address and tax year.
- Review first-half, second-half and delinquent amounts.
- Check the processor fee before continuing.
- Save the final payment confirmation.
King County Online Payment Fees in 2026
Fees matter on a large property-tax payment. King County states that electronic processing fees are charged by the payment processor and are not retained by the county.
The county FAQ lists a flat $0.55 processor fee for an accepted eCheck payment.
The current county FAQ and payment system list a 2.35% service fee with a $2 minimum for debit and credit card transactions.
King County says there is no electronic processor fee for check payments made by mail. Follow current mailing instructions and keep postmark proof.
In-person check payments do not carry the electronic processor fee. Card payments can still be subject to the processor charge.
Fee check: Processor fees can change. Read the amount displayed by the official payment system before authorizing a large transaction.
King County Property Tax Due Dates for 2026
First-half property taxes are due. If the total annual tax is less than $50, the full year’s tax is due.
King County also lists April 30 for personal-property listing forms.
Monthly late charges begin after the first-half deadline when taxes remain delinquent.
The 2026 overview shows July 1, but the Board explains that a petition is due by the later of July 1 or 60 days after the valuation or determination notice was mailed.
The annual application deadline for King County’s limited-income deferral program is September 1.
The second-half property-tax installment is due October 31 when the first half was paid as required.
Monthly late charges begin on an unpaid second-half balance after the October 31 deadline.
King County states that payments must be paid or postmarked by the applicable deadline. Keep proof if mailing close to a due date.
- Open King County’s 2026 property-tax page.
- Match the tax year to your bill.
- Confirm which half is due.
- Check whether the account already shows payment.
- For appeals, use the date printed on the Assessor notice to calculate the 60-day rule.
- Save any confirmation or mailed-payment proof.
The payment deadline and assessment-appeal deadline are separate. Paying a bill does not remove your assessment appeal rights, and filing an appeal does not automatically stop payment obligations.
How to Read a King County Property Tax Bill
Use this number consistently when searching, paying, mailing a check or contacting Treasury.
The King County tax-bill guide explains that the annual tax is calculated from taxable value and the levy rate.
The applicable levy rate depends on the taxing districts that serve the parcel.
Property-tax dollars can fund the state, county, cities, schools and special-purpose districts.
A King County bill may contain other charges or assessments in addition to ordinary ad valorem property tax.
Check which installment remains unpaid rather than assuming the displayed annual total is currently due.
If the bill increased, compare assessed value, levy code, voter-approved measures, exemptions and taxing districts—not just the market value of the property.
How King County Property Tax Is Calculated
King County’s levy-rate guidance uses a simple starting formula: divide assessed or taxable value by 1,000 and multiply by the applicable levy rate. The exact bill can also contain other charges.
- Assume taxable value is $800,000.
- Assume the applicable combined levy rate is $9.50 per $1,000.
- $800,000 ÷ 1,000 = 800.
- 800 × $9.50 = $7,600 estimated ad valorem tax.
- Add or subtract only the actual charges, exemptions and adjustments shown on the official account.
The $9.50 rate above is an illustration, not a current rate for a specific King County parcel.
Check 2026 King County Levy ReportsKing County reports about $8.4 billion in total property taxes for 2026, up about $770 million from the prior year. The county also explains that voter-approved measures are often a major driver of tax increases and that King County government itself receives about 20% of the property-tax total.
King County Senior, Disabled and Veteran Property Tax Relief
Washington law provides property-tax exemption and deferral programs that King County administers for eligible residents. These are not general exemptions for every homeowner.
King County currently states that exemption eligibility can include qualifying age, disability or disabled-veteran status, ownership and occupancy, and household income requirements.
The current King County material lists household income under $84,000 based on 2025 earnings for the senior/disabled exemption program.
The exemption applies to a qualifying residence under Washington program rules; ownership and occupancy documentation may be required.
King County encourages online applications because paper submissions generally take more staff processing time.
- Open the current King County tax-relief page.
- Choose the senior/disabled/veteran exemption or the appropriate deferral program.
- Review age, disability, veteran, ownership and occupancy requirements.
- Check the current income definition and limit.
- Prepare income and eligibility documents.
- Submit through the official King County application route.
- Save your application confirmation and respond to follow-up requests.
An exemption and a deferral are different. An exemption can reduce tax under program rules; a deferral postpones payment and can create a lien with interest.
King County Limited-Income Property Tax Deferral
King County’s limited-income deferral is not a grant or permanent tax cancellation. It can postpone part of the property-tax payment for qualifying homeowners.
The current county page lists at least five years of property ownership as an eligibility condition.
The applicant must meet the program’s residence and minimum annual occupancy rules.
The current limited-income deferral page lists prior-year household income of $57,000 or less.
King County lists September 1 as the annual application deadline.
The county says the first half must be paid before applying to defer the second installment under this program.
Deferred taxes and interest become a lien until repaid. The program must be reapplied for when future deferral is requested.
- Confirm you meet ownership and occupancy requirements.
- Check the current household-income limit.
- Verify the first-half tax has been paid.
- Review equity requirements.
- Read how interest and the lien work.
- Apply by September 1 and save proof.
How to Appeal a King County Property Assessment
An assessment appeal is about the property’s valuation or an Assessor determination. It is not the same as disputing a payment processor fee or asking Treasury to change the tax rate.
Deadline correction: Do not rely on “July 1” alone. King County’s Board of Equalization states that petitions generally must be filed by the later of July 1 of the assessment year or 60 calendar days after the valuation change or other determination notice was mailed.
- Open the King County assessment appeal page.
- Use your valuation notice mailing date.
- Compare the 60-day date with July 1.
- Use the later applicable deadline under the county instructions.
- Prepare the petition and evidence.
- File through an accepted method and save confirmation.
Do not wait for the property-tax bill to challenge a valuation notice. The assessment year comes before the tax-payable year, so the appeal period can occur many months before payment is due.
Mortgage Escrow: Check Before Paying Yourself
If your mortgage payment includes escrow, the servicer may send the tax payment directly to King County. Receiving a tax statement does not automatically mean you should make another payment.
A tax bill can be informational even when escrow is responsible for payment, but the owner should still verify that the payment actually posts.
Overpayments, Duplicate Payments and Refunds
A common King County overpayment situation happens when both the homeowner and mortgage servicer submit money. Paying both current installments early is not automatically an overpayment; it can simply mean the full year is paid.
- Search the King County account for both transactions.
- Compare the homeowner bank record with the mortgage escrow record.
- Confirm that the second transaction was truly extra.
- Save both receipts or payment records.
- Allow normal posting time before assuming a payment was lost.
- Contact Treasury Operations with the account number and proof.
Do not submit another payment only because the website has not updated immediately. King County says account records can take up to about a week to reflect a received payment, and a rejected bank transaction can later be reversed.
Late and Delinquent King County Property Taxes
Monthly late charges can begin May 1. Use the live account to calculate what is currently due.
King County says delinquent first-half real-property taxes can generally still be paid before the second-half deadline with applicable late charges.
Monthly late charges begin against an unpaid second-half balance starting November 1.
King County provides payment-plan information for qualifying delinquent property-tax situations. Eligibility and terms must be checked directly.
Foreclosure-related accounts can include additional costs. Use the Tax Foreclosure Unit rather than guessing from an older balance.
Delinquent personal-property accounts can have different online payment limitations, so contact Treasury when the system does not offer the needed transaction.
- Open the official payment system.
- Search the correct tax account.
- Review the current delinquent amount and year.
- Do not calculate late charges from an old statement yourself.
- If foreclosure is involved, contact the Foreclosure Unit for the actual payoff.
- Save all payment and correspondence records.
Mail, In-Person and Phone Rules
201 South Jackson Street, Suite 710, Seattle, WA 98104. Write the tax account number on the check and follow the current remittance instructions.
King Street Center, 201 South Jackson Street, Second Floor, Seattle. Current official hours are Monday through Friday, 8:30 a.m. to 4:30 p.m., excluding holidays.
Treasury staff can help with real-property tax questions, but King County says property-tax payments are not processed by phone.
Use the foreclosure contact for accounts already in the tax-foreclosure process or when an exact foreclosure payoff is needed.
Mailing tip: King County accepts timely postmarks for ordinary installment deadlines. Keep the remittance stub when available, write the account number on the check and save mailing evidence if sending payment close to April 30 or October 31.
King County Personal Property Tax Is Different
Business personal property and certain mobile-home tax accounts are not identical to ordinary real-estate accounts.
King County’s payment system says real-property tax account numbers are generally 10 or 12 digits.
King County says personal-property account numbers are generally 8 digits. The separate 4200 number shown on some statements is not included.
The county’s 2026 calendar lists April 30 for personal-property listing forms.
Treasury lists a separate contact for mobile homes and commercial personal-property tax questions.
Do not apply real-estate parcel assumptions to a business or mobile-home personal-property account. Confirm the account type first.
King County Property Tax Troubleshooting
Likely cause: wrong identifier or parcel search.
Next step: use Parcel Viewer or eReal Property and confirm the address before paying.
Likely cause: processing delay, bank rejection or wrong account.
Next step: compare bank and county records and keep the transaction confirmation.
Likely cause: valuation or property-record issue.
Next step: use the Assessor and preserve the July 1 / 60-day Board deadline.
Likely cause: application status, eligibility, documentation or program-year issue.
Next step: contact the Assessor exemption team rather than Treasury payment support.
Likely cause: lender timing or servicing error.
Next step: contact the servicer and monitor the official account before the deadline.
Likely cause: an omitted assessment for an improvement that should have been assessed earlier.
Next step: identify the omit and roll years and ask Treasury how the specific amount is due.
Problem → office → action is the fastest rule: assessment problem → Assessor/BOE; payment problem → Treasury; foreclosure problem → Foreclosure Unit.
Documents Worth Keeping
Tax account number, parcel number, current statement, live balance, due date and escrow information.
Confirmation number, receipt, bank transaction, canceled check or mailing proof.
Ownership, occupancy, income, age, disability or veteran documentation and application confirmation.
Valuation notice, property details, comparable sales, photos, repair estimates and filing confirmation.
Both payment records, mortgage escrow statement and official account history.
Current payoff, old statements, payment-plan documents and foreclosure correspondence if applicable.
King County Property Tax Terms
- Tax Account Number
- The number used for King County billing, payment, statements and tax-account customer service.
- Parcel Number
- The property identifier used by the Assessor, GIS and parcel research tools.
- Assessed Value
- The property value determined by the Assessor for property-tax purposes.
- Levy Rate
- The combined rate applied to a property’s taxable value based on the taxing districts serving that parcel.
- Board of Equalization
- The county body that hears eligible property-assessment appeals.
- Deferral
- A program that postpones eligible tax rather than eliminating it; deferred tax and interest can become a lien.
Official King County Property Tax Links
Related Property Tax Guides on CountyPropertyTaxes.us
These links were selected from currently live site content because they support a specific next task rather than sending users to unrelated county pages.
King County Property Tax FAQs
When are King County property taxes due in 2026?
King County lists April 30, 2026 as the first-half property-tax due date and October 31, 2026 as the second-half due date. If total annual taxes are less than $50, the full amount is due April 30.
How do I search King County property tax by address?
Use the King County Parcel Viewer or Assessor property-information tools to search by address. Confirm the parcel, then use the parcel or tax account number in the official property-tax payment system.
What are King County online property tax payment fees in 2026?
The current county FAQ lists a $0.55 eCheck processing fee and a 2.35% fee with a $2 minimum for debit and credit card payments. The processor collects the fee, not King County.
What is the King County property assessment appeal deadline?
The Board of Equalization states that a petition generally must be filed by the later of July 1 of the assessment year or 60 calendar days after the valuation-change or other determination notice was mailed.
Who qualifies for King County senior or disabled property tax relief?
Eligibility depends on the specific Washington exemption or deferral program. Current King County guidance includes qualifying age, disability or disabled-veteran status, ownership and occupancy, household income and other program rules.
Can I pay King County property tax by phone?
No. King County’s FAQ states that staff can assist taxpayers with the online process but do not process property-tax payments by phone.
What if my mortgage company pays my taxes?
Check both your mortgage escrow information and the live King County account before paying personally. The taxpayer remains responsible for making sure the tax is paid on time.
Where do I mail a King County property tax payment?
Current county instructions list King County Treasury Operations, 201 South Jackson Street, Suite 710, Seattle, WA 98104. Write the tax account number on the check and keep mailing proof.
Bottom Line
For King County property tax, start with the parcel or tax account. Use Treasury Operations for bills, payments, receipts, refunds and delinquency. Use the Assessor for property value and tax relief. If you disagree with an assessment, calculate the Board of Equalization deadline using the later-of-July-1-or-60-days rule instead of assuming July 1 is the only deadline.
Find Account Pay Safely 2026 Dates Tax Relief Appeal Official LinksMaterially reviewed and updated using current King County 2026 tax, payment, assessment, relief and appeal guidance: August 27, 2026.