2026 Property Tax Due Dates
Installment 1
April 30
First half
Installment 2
October 31
Second half
Penalty: 3% June 1, +8% December 1Grace period: None
Payment Methods
Online, Mail, In-Person
Cowlitz County Treasurer
Phone
(360) 577-3060Office Hours
Mon-Fri 8am - 5pm
How to Pay
Online
Pay using credit card or e-check
By Mail
Mail check payable to Cowlitz County Treasurer
In Person
Visit the Treasurer's office — 207 N. 4th Ave., Room 202, Kelso WA 98626, Mon-Fri 8am - 5pm
Other Counties in Washington
About Cowlitz County
Cowlitz County is a county located in the U.S. state of Washington. As of the 2020 census, its population was 110,730. The county seat is Kelso, and its largest city is Longview.
Source: Wikipedia — content available under CC BY-SA 4.0
Related Resources
Get Deadline Reminders
We'll email you 336 hours before your property taxes are due.
Due dates shown are for reference only. Contact your county treasurer's office to confirm official deadlines before making payments.