The Riverside Township Assessor's office hours are Monday – Friday, from am – pm. Appointments are encouraged for in-person meetings.The Cook County Assessor's Office has adjusted their 2022 Exemption Application mailing timeline as follows. Summary. In April 2023, Cook County prioritized three research questions regarding Illinois' homestead exemptions for further study. Take control of your Riverside property taxes with ease. The BOR accepts exemption applications for approximately 30 days, four times each year. You can apply online for any of these exemptions through the Cook County Assessor's Office. Complete form BOE-266, Claim for Homeowners'. Property Tax Exemption. Close submenu ( Property Tax Information) Property Tax Information.