By mail: to Cowlitz County Treasurer, 207 4th Ave. N, Kelso, WA 98626. Make checks payable to: Cowlitz County Treasurer, please have postmarked before the April 30th deadline.
Secure drop box: at the North and South entrance of the Administration Building located at 207 4th Ave. N and outside the entrance to the Treasurer's Office. Please pay by check, cashier’s check or money order. Please do not pay by cash in the drop box.
Drive up drop box: located in the North parking lot of the Administration Building at 207 4th Ave N. Please pay by check, cashier’s check or money order. Please do not pay by cash in drop box.