Is There a Cap on Property Taxes in Illinois? (A Clear Real-World Explanation)
By Harsha N Hegde
Many Illinois homeowners search for a simple answer to a simple question: Is there a cap on property taxes in Illinois?
The short answer is NO, Illinois has no cap on your property tax bill.
Your bill can rise sharply depending on assessments, local levies, voter-approved referendums, and bond payments.
What Illinois actually has is a Property Tax Extension Limitation Law (PTELL), a law many people casually call “tax caps”. PTELL does not cap your property tax bill. It only limits how fast a non-home-rule taxing district’s total tax extension can grow. That’s a crucial difference.
What Illinois Does Not Have
There is no law limiting how much your own tax bill can increase in any given year. Your bill can rise 10%, 20%, even 40% in reassessment years. Nothing in Illinois tax law stops that.
What Illinois Actually Has: PTELL
PTELL (Property Tax Extension Limitation Law) applies mainly to non-home-rule taxing districts in Cook County, the collar counties, and other counties that have adopted it. Here is Illinois DOR’s official map showing which counties adopted PTELL.
PTELL limits the growth of a district’s tax extension on existing property. A tax extension is the total amount of taxes billed by a taxing district for the year.
For existing property:
- A district’s extension may grow only by:
- 5%, or
- the percentage change in CPI,
whichever is lower.
Additionally, PTELL allows:
- An extra extension for new construction, and
- Extra extension for voter-approved rate increases (referendums).
PTELL applies broadly to district funds
The Illinois Department of Revenue notes that PTELL applies to almost all district funds (insurance, self-insurance, tort liability, IMRF, FICA, audit, etc.) except those specially exempt under 35 ILCS 200/18-185.
The county clerk may need to calculate a separate limiting rate
Under 35 ILCS 200/18-195, a county clerk may need to calculate a separate limiting rate for a district. If reductions are required, the clerk proportionally reduces the rate for each PTELL-regulated fund so the total extension stays within limits.
PTELL is independent of Truth-in-Taxation
PTELL has nothing to do with local “Truth-in-Taxation” hearing requirements. A district may hold a TNT hearing and still be under PTELL, or vice-versa. The two laws operate independently.
What PTELL does not do:
- It does not cap your assessment.
- It does not cap your individual bill.
- It does not stop large increases caused by bonds, new construction, or referendums.
- It does not guarantee a maximum increase on your specific property.
A Real Example: How PTELL Affects a Homeowner
Let’s use typical Cook County–style numbers.
Last year
- District extension: $100 million
- CPI: 3%
PTELL lets the district collect:
- $103 million (3% increase) on existing property
Assessments rise
District-wide EAV increases:
- $1 billion → $1.15 billion (+15%)
Your home also rises 15%:
- $100,000 → $115,000
PTELL forces the tax rate down
To keep the extension at $103 million:
- Last year’s rate: 10%
- This year’s rate: 103M / 1.15B = 8.96%
Your bill
- 115,000 × 0.0896 = $10,304
Last year: $10,000
This year: $10,304 (a 3% increase)
Your assessment rose 15%, but your bill rose 3%—matching PTELL’s limit on the district’s extension.
When Your Assessment Rises More Than the District Average
If your property jumps 25% while the district rises only 15%:
- Your new EAV: 125,000
- Tax: 125,000 × 0.0896 = $11,200
Your bill rises 12%, even though PTELL capped district extension growth at 3%.
PTELL does not protect an individual property from above-average assessment increases.
When Your Assessment Rises Less Than the District Average
If your home rises only 5%:
- Your new EAV: 105,000
- Tax: 105,000 × 0.0896 ≈ $9,408
Your bill drops ~6%.
PTELL redistributes tax burden within the district.
Referendums and Debt Override PTELL Limits
PTELL cannot stop increases from:
- school construction bonds,
- operating referendums,
- debt service, and
- special taxing districts.
These sit outside the normal CPI/5% limit.
New Construction Sits Outside PTELL Limits
Districts get extra extension for new construction, on top of the main PTELL cap.
This is why fast-growing suburbs can see noticeably higher total extensions.
Key Terms
- Tax extension: total taxes billed by a district
- Taxing district: school, park, library, fire protection district, etc.
- Limiting rate: maximum rate allowed under PTELL to stay within the extension limit
The Bottom Line
Illinois does not cap your individual property tax bill.
PTELL only caps how fast taxing districts can grow their total extension on existing property. It does not cap assessments, does not cap individual tax bills, and does not stop increases driven by referendums, bonds, or uneven assessment growth.
Once you understand PTELL’s limits, you can focus on the part you can control: making sure your assessment is fair and appealing when it isn’t.
Glossary of Key PTELL Terms
Tax extension:
The total amount of property taxes billed by a taxing district in a given year. PTELL limits how fast this total extension can grow for non-home-rule districts.
Taxing district:
A unit of local government that can levy property taxes—such as a school district, park district, library district, fire district, or township.
Non–home rule district:
A local government that does not have home-rule taxing powers. Most school, park, library, and fire districts are non–home rule, so PTELL applies to them.
Limiting rate:
The maximum tax rate a district is allowed to use under PTELL so its total extension on existing property stays within the allowable growth limit.
About the Author
Harsha N Hegde is the founder of squaredeal.tax, a DIY platform that helps homeowners protest unfair property tax assessments. He has helped thousands of homeowners save money using comps-based evidence and practical guidance.
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