Appeals may only be filed during certain periods of time. Please read the general information about appeals for important information about rules for filing and deadlines for your area. You do not need to hire an attorney to file an appeal and filing is free at our office.
My property was recently reassessed. How did the Cook County Assessor's Office calculate its fair market value?
Our analysts use market data to produce fair market values of properties. To calculate a commercial property’s fair market value, our analysts use multiple data sources to find market ranges of information like rents, vacancy rates, expense rates, and cap rates of similar income-producing properties, in and around its neighborhood. Read more on our commercial valuations page.
What is the difference between fair market value and assessed value?
Property owners receive two updated values from the Assessor's Office every three years: their property's assigned fair market value and its corresponding assessed value.
Fair Market Value: The Assessor's Office has a statutory duty to assign a fair market value to all taxable properties in Cook County. A property's fair market value is our determination of the amount for which the property could be sold in the due course of business, not under duress, between a willing buyer and willing seller. Our office uses real estate market data, information submitted by property owners, and computer modeling to make that determination.
Assessed Value: Only a percentage of a property’s fair market value is used in calculating its tax bill. Per Cook County ordinance, a property's percentage (its level of assessment) depends on its major class type. For residential properties like single-family homes, 10% of fair market value is assessed for taxation, and for most commercial properties, 25% of fair market value is assessed for taxation. A commercial property with a fair market value of $300,000 and a level of assessment of 25% of fair market value has an Assessed Value of $75,000.
You may submit your appeal and supporting documents entirely online when the property's township is open for appeals.
Real Property Income & Expense
The Real Property Income & Expense (RPIE) statement is required when the subject of an appeal is an income-producing property, in whole or in part, per Rule 20. An online filing is required if:
- the income from this property was reported to the IRS on a Schedule E or Form 8825
- the lessee of this property was party to a net or triple net lease, and therefore is responsible for the property's real estate taxes
If the property type is not supported by the online form, the PDF form is available:
- Real Property Income and Expense Worksheet (RPIE)
- Real Property Income and Expense Worksheet (RPIE) Instructions
Note that any data and documentation supporting the appeal must be submitted concurrently with the appeal..
- Industrial/Commercial Appeal
- Property Summary Sheet
- Attorney Representative Authorization
- Appraisal Summary Sheet
- Owner Occupancy Affidavit
- Rent Roll - Apartments
- Rent Roll - Industrial/Commercial
- Sales Questionnaire
- Vacancy Affidavit
- Vacancy Affidavit - 10 or More Stories
- Demolition Affidavit
- General Affidavit
- Field Check Request Letter
Where do I find my PIN?
Your 14-digit Property Index Number (PIN) is printed on your tax bill, your property closing documents and deed, and notices from the Assessor's office (such as your assessment notice).
Enter PIN to see property details
Don’t know the property’s PIN? Search by address.