Instructions: Mail (or submit in person) this application and supporting documents to a Cook County Assessor's Office. The BOR accepts exemption applications for approximately 30 days, four times each year.Senior Citizen Homestead Exemption. The Cook County Assessor's Office administers property tax exemptions that may contribute to lowering veteran's property tax bill. The Longtime Occupant Homeowner Exemption enables property owners to receive an expanded Homeowner Exemption with no maximum exemption amount. The deadline for homeowners to apply for current property tax exemptions (tax year 2021) is Friday, August 26, 2022. Time permitting, you may receive an adjusted bill and pay a reduced amount reflecting your omitted exemption(s).