Cook County, home to Chicago and 5 million residents, uses Illinois's distinctive four-step property tax calculation: fair market value becomes assessed value, then equalized assessed value (EAV), then net EAV after exemptions, and finally a composite tax rate is applied. This guide walks through every step and explains the exemptions — including the General Homestead Exemption and Senior Citizen Homestead Exemption — that many homeowners never file for.
How the bill is built
Illinois calculates property tax differently from nearly every other state. Start with your home's fair market value (FMV). Multiply by the assessment ratio (10% for residential property in Cook County — a unique classification) to get your locally Assessed Value (AV). Then the Illinois Department of Revenue applies a state equalization factor (called the "multiplier") — for Cook County, this is approximately 3.0355 — to calculate your Equalized Assessed Value (EAV).
From your EAV, subtract any exemptions you qualify for: $10,000 for the General Homestead Exemption, plus an additional $8,000 if you are 65 or older. What's left is your Net EAV, and that is multiplied by the local composite tax rate — the sum of every taxing district levying against your parcel (schools, city, county, park district, library, township, community college, etc.).
2026 Cook County rate breakdown (composite rate % of EAV, Chicago district)
| Taxing entity | Rate |
|---|---|
| Chicago Public Schools (Board of Ed) | 3.8142 |
| City of Chicago | 1.5762 |
| Cook County | 0.4303 |
| Chicago Park District | 0.3270 |
| Metropolitan Water Reclamation District | 0.3680 |
| City Colleges of Chicago | 0.1410 |
| Chicago Public Library | 0.1490 |
| Combined total | 6.8057 |
Exemptions that reduce your EAV
Illinois property tax exemptions work by subtracting from your Equalized Assessed Value (EAV) — not from your tax bill directly. The dollar value of each exemption depends on your local composite rate: in a district with an 8% composite rate, a $10,000 EAV reduction saves roughly $800 per year.
General Homestead Exemption (GHE) — $10,000 in Cook County
Every Illinois homeowner who occupies their primary residence qualifies. The exemption reduces your EAV by $10,000 in Cook County and $6,000 elsewhere in Illinois. In Cook County, the GHE is generally auto-renewed after initial application; in other counties, you typically apply once and it continues annually.
Senior Citizen Homestead Exemption — additional $8,000 EAV reduction
Homeowners 65 or older receive an additional EAV reduction on top of the General Homestead Exemption. File Form PTAX-324 with your Cook County Assessor's Office — the initial application usually requires proof of age and residency; some counties require annual renewal.
Senior Citizen Assessment Freeze (the "Senior Freeze")
If you are 65+ with total household income under $65,000 (in Cook County; $75,000 in some other counties), you can apply for an EAV freeze that locks your home's EAV at its base-year value. Your tax bill can still rise if rates increase, but you are protected from rising assessments. Requires annual renewal with income documentation (Form PTAX-340).
Returning Veterans' Homestead Exemption — $5,000 for 2 years
Veterans returning from an armed conflict receive a $5,000 EAV reduction for each of the two tax years following their return.
Veterans with Disabilities (SHEVD) — up to full exemption
Veterans with a service-connected disability receive a tiered EAV reduction: $2,500 (30–49% disability), $5,000 (50–69%), or all EAV up to $250,000 (70%+ — effectively a full exemption for most primary residences). Apply with Form PTAX-342.
Appealing your assessment
If you believe your Chicago-area assessed value is too high, you can appeal to your Board of Review (called the "Cook County Board of Review" in Cook; "Board of Review" in other counties). Deadlines vary by township and reassessment cycle — for Cook County, the window opens 30 days after township reassessment notices are mailed. Successful appeals can reduce your AV (and therefore your EAV and your bill) for the year.
In Cook County specifically, the triennial reassessment schedule means your property is reassessed every three years. The three regions — North suburbs, South suburbs, and the City of Chicago — rotate, so know which year your township is up.