First half real estate and mobile home taxes must be paid by September 30^th. Statement coupons must also be submitted with payment. Washington County Treasurer Jeffrey Garrett says payments can be made in person or deposited in the drop box at the Washington County Courthouse, mailed to the Washington County Treasurer at PO Box 889 in Washington, or paid online at iowatreasurers.org ^[1].  Payments must be postmarked on or before September 30^th to avoid penalty.