Due Date: The regular deadline to file is closed, however homeowners can file for a Certificate of Error to correct past tax bills. The deadline for homeowners to apply for property tax exemptions is Monday, April 29.The BOR accepts exemption applications for approximately 30 days, four times each year. First-time applicants must have been the occupants of the property as of January 1 of the tax year in question. The August 4, 2023 deadline to apply for property tax exemptions for Cook County homeowners is coming soon. The deadline for homeowners to apply for current property tax exemptions (tax year 2021) is Friday, August 26, 2022. This form is used to apply for the Homeowners' Property Tax Exemption in California. Homeowners have until April 9 to apply for property tax exemptions. First-time applicants must have been the occupants of the property as of January 1 of the tax year in question. All applications must be submitted online through the Smartfile E-Filing Portal.