Cook County, IL Local Taxes & Fees: Business Tax Classification (2026)
Key Facts
- Class 5a (commercial)
- 25% of market value
- Class 5b (industrial)
- 25% of market value
- Class 2 (owner-occ. home)
- 10% of market value
- Incentive classes 6b/7a/7b/8
- 10% for up to 12 years
- Administered by
- Cook County Assessor's Office
Summary
Cook County taxes business real estate under its own classification system: commercial (Class 5a) and industrial (Class 5b) property is assessed at 25% of market value, more than double the 10% rate for owner-occupied homes.
Class 5a. All real estate not included in Class 1, Class 2, Class 3, Class 4, Class 5b, Class 6b, Class C, Class 7a, Class 7b, Class 7c, Class 7d, Class 8, Class 9, Class S or Class L of this Section. ... Class 5b. All real estate used for industrial purposes as defined herein and not included in any other class.
Full Breakdown
Cook County's Real Property Assessment Classification Ordinance (Code §§ 74-60: 74-75) sorts every parcel into a tax class that sets its assessment level, the percentage of market value the Assessor taxes. General commercial real estate is Class 5a and industrial property is Class 5b, both assessed at 25%, versus 10% for owner-occupied homes (Class 2) and most apartment buildings (Class 3, § 74-64). A business building new industrial or commercial space, substantially rehabbing an existing structure, or reoccupying abandoned property can apply to the Assessor for an incentive class (6b, 7a, 7b, 8), which drops the assessment level to 10% for up to 12 years with municipal or County Board consent.
Violations & Fines
Losing or misusing an incentive classification reverts the property to full Class 5 (25%) assessment, and the owner must reimburse the County Collector the tax difference for the period the incentive was wrongly applied.
Frequently Asked Questions
What tax class applies to a Cook County business property?
Can a business qualify for a lower assessment?
Sources & Official References
Other rules in Cook County
Compare Cook County to another location·View the Illinois local taxes & fees overview
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