Classifications of Real Property

Property class codes are used to classify property types. Some factors that determine a classification code are the stories, square footage, age, and purpose. A common classification code is a 2-03, which the Cook County Assessor’s Office (CCAO) defines as a one-story residence that is 1,000 to 999 square feet. 

For the purposes of property assessment, every Property Index Number (PIN) is assigned a classification code. The classification of a property determines the level of assessment. There are classification codes unique to unimproved real estate and exempt, residential, multi-family, not-for-profit, commercial, industrial, and incentive properties. 

To view a full list of classification codes for real property, click the button below. 

Classification Codes

Follow the steps below to find your property's classification code: 

Find the Property Classification

The property classification code is listed under the Tax Details section. 

Access more in-depth property details

Toward the bottom of the page, click on the blue button that reads Access More In-Depth Property Details Here

Learn about annual changes and amendments

To learn about annual policy changes pertaining to assessments and appeals, review the Official Appeal Rules of the Cook County Assessor. Any changes related to property classifications are announced and listed here. Additionally, the CCAO hosts an annual meeting that reviews all the major changes implemented. The virtual meeting can be accessed on the same page.

Information about Class 3-18 properties

You can find information about the amended 3-18 property definition that was implemented in 2023 under Rule 25 of the Official Appeal Rules. The amended 3-18 property classification definition is shown below. 

Mixed-use commercial/residential building with apartment and commercial area totaling 7 units or more or between 20,000 to 99,999 square feet of building area, with the commercial component of the property consisting of no more than 35% of the total rentable square footage.  

If the CCAO determines that a property no longer qualifies as a 3-18, the following will occur: 

  1. The CCAO will send a letter to the property owner notifying them of the potential change. 
  2. The CCAO will send a field inspector to visit the property to conduct an official inspection.

    - If the field inspector determines that the commercial rentable square footage of one or more of the buildings is greater than 35% of the total rentable square footage, the CCAO will no longer classify the property as a 3-18. Instead, the property’s classification and the building record(s) will split into two classifications based on the percentage of building square feet attributable to commercial and residential use.

    -If the classification of the building is split, the residential portion of the building will continue to be assessed at 10% of its market value and the commercial portion of the building will be assessed at 25% of its market value based on its use. This change may lead to an increase in your property tax bill. 

  3. The CCAO will send a letter to any property that is subject to this change, containing detailed information about the reclassification before receiving the official Reassessment Notice.