Late fees for real estate and mobile home taxes begin October 1st. Half of real estate and mobile home taxes must be paid by September 30th. Starting October 1st, a late fee will be assessed to taxes. Jeff Garrett, Washington County Treasurer, explains a penalty of 1.5% per month, rounded to the nearest whole dollar, with a $1 minimum per parcel will be attached. Payments should be accompanied by statement coupons. Payments can also be made online at iowatreasurers.org or in person at the treasurer’s office in the Washington County Courthouse. Washington County tax payers also have the option to put payments in the drop box by the south entrance of the courthouse.