When property taxes are due in King County, WA — plus the official payment portal and what happens if you're late.
| Instalment | Due date | Notes |
|---|---|---|
| First half | April 30, 2027 | Full year becomes delinquent June 1 if unpaid |
| Second half | October 31, 2027 | Delinquent after October 31 |
Interest and penalty accrue from June 1 on unpaid first half.
First half: April 30, 2027. Second half: October 31, 2027.
Interest and penalty accrue from June 1 on unpaid first half.
Pay online through kingcounty.gov, the county's own payment portal, or by post or in person at the treasurer's office.
Two halves, April and October. Counties shift dates when billing is delayed, so confirm against the county source linked on this page.
Most counties offer instalment plans or partial payment — ask the treasurer before the due date, not after. Once the bill is delinquent the options shrink and the fees start.
Unpaid property tax is a lien on the property in most states, which your servicer may pay and then bill you for, with fees. It does not disappear.
StacyApproved is an independent reference and is not a government agency. Deadlines change and exceptions apply — always confirm with your county treasurer using the official link on this page. Nothing here is tax, legal or financial advice.