Many homeowners are unaware of property tax exemptions that can translate into savings and help contribute in lowering property tax bills. The Certificate of Error process provides homeowners an opportunity to redeem missing exemptions for up to three prior years.
Illinois law provides the Certificate of Error procedure to allow the Cook County Assessor to apply changes to a property tax bill that has already been issued. It is a way to make a correction after the assessment for that tax year is finalized.
Homeowners can now apply for multiple exemptions and tax years using one consolidated form. Please carefully read through the eligibility and required document section of each exemption. Please note that Certificate of Error applications can be denied.
Missing Property Tax Exemptions? Homeowners can apply for Certificates of Error.
If a homeowner was eligible for a homestead exemption in tax years 2025, 2024, 2023, 2022, and 2021 and the exemption was not applied to the paid property tax bill, a refund can be obtained through the Certificate of Error process.
The property must have been eligible in the tax year in which a homeowner is applying. A photo ID along with other required supporting documentation must be supplied with the application to demonstrate eligibility. For example, to apply for a Homeowner Exemption Certificate of Error for Tax Year 2021, required documents must demonstrate that the home was the primary place of residence as of January 1, 2021.
There are two types of Certificates of Error.
- One is for missing exemptions for past tax years.
- The other is to correct a property's assessed valuation after a tax bill has been issued.
The best part? You can apply online! Click here to apply online.
Example Scenario: A homeowner who is 68 years old recently learned that she has been qualified for the Senior Exemption since she was 65 years old. This homeowner can apply for Certificates of Error to receive refunds for prior eligible years.
Click here to download a Certificate of Error brochure.
Different types of exemptions include:
Homeowner Exemption
Most homeowners are eligible for this exemption if they own and occupy the property as their principal place of residence. Once this exemption is applied, the Assessor’s Office auto-renews it for you each year. This exemption provides savings by reducing the equalized assessed value of an eligible property.
Automatic Renewal: Yes, this exemption automatically renews each year.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Senior Exemption
Most senior homeowners are eligible for this exemption if they are 65 years of age or older and own and occupy their property as their principal place of residence. Once this exemption is applied, the Assessor’s Office automatically renews it for you each year. A Senior Exemption provides property tax savings by reducing the equalized assessed value of an eligible property.
Automatic Renewal: Yes, this exemption automatically renews each year.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Low-Income Senior Citizens Assessment Freeze Exemption "Senior Freeze"
Most homeowners are eligible for this exemption if they meet the requirements for the Senior Exemption and have a total household annual income of $65,000 or less in the calendar year 2021. This exemption provides significant savings by "freezing" the equalized assessed value of an eligible property.
Automatic Renewal: No, this exemption must be filed annually.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Persons with Disabilities Exemption
Homeowners eligible for this exemption this year must be disabled or become disabled during the 2021 tax year. This exemption provides property tax savings with an annual reduction in the equalized assessed value of a property. Click the button below to learn more about eligibility and the documents required to apply.
Automatic Renewal: Yes, this exemption will automatically renew due to new state legislation.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Returning Veterans Exemption
Provides veterans returning from active duty in armed conflict with a reduction in the equalized assessed value of their property – for each taxable year in which they return. This exemption must be filed annually. Click the button below to learn more about eligibility and the documents required to apply.
Automatic Renewal: No, this exemption must be filed annually.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Veterans with Disabilities Exemption
Provides veterans with a service-connected disability as certified by the U.S. Department of Veteran Affairs with a reduction in the equalized assessed value (EAV) of their property. The amounts of those EAV deductions depend on the level of disability. Click the button below to learn more about eligibility and the documents required to apply.
Automatic Renewal: No, this exemption must be filed annually.
Missing Exemptions: Can be filed for tax years 2021, 2020, 2019, and 2018.
Learn more here:
Long-Time Homeowner Exemption
Only 2% of homeowners in Cook County qualify for this exemption. This exemption provides homeowners with an expanded Homeowner Exemption with no maximum exemption amount. In addition to meeting income and residency requirements, applicants must also have a significant assessment increase that exceeds the maximum amounts set by the state legislature. Applications will be mailed directly to potentially eligible homeowners.
Automatic Renewal: No, this exemption must be filed annually.
Learn more here:
Home Improvement Exemption
Allows homeowners to add improvements to their home that add to its value (for example, by increasing the building’s square footage, or repairing after structural flood damage) without being taxed on up to $75,000 of the added value for up to four years.
Automatic Renewal: Yes. This exemption lasts up to four years.
Application Due Date: No application is required. Our office automatically applies this exemption to eligible properties.
Learn more here:
*Please Note: Equalized Assessed Value (EAV) is not the amount of your taxes. The EAV is the taxed value of the property. A reduction in EAV is not the dollar amount of reduction of a tax bill. Each property's tax bill is affected by its EAV and its local tax rate that year.
To contact the Cook County Assessor's office please see below:
By phone - (312) 443-7550
