Illinois Property Tax Increase Limit: Is There a Cap? How PTELL Works

By Harsha N Hegde

Many Illinois homeowners ask: Is there a cap or limit on property tax increases 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 the Property Tax Extension Limitation Law (PTELL), a law many people casually call the Illinois “tax cap.” 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.

Does PTELL Apply in Cook County?

Yes. PTELL applies to many non-home-rule taxing districts in Cook County. But it does not cap an individual Cook County homeowner’s assessment or property tax bill.

That distinction matters during Cook County’s triennial reassessment cycle. If your property’s assessed value rises faster than the rest of the taxing district, your individual bill can increase by much more than the PTELL limit.

What Is PTELL in Illinois?

PTELL is Illinois’ Property Tax Extension Limitation Law. It limits annual growth in the total property taxes collected by many non-home-rule taxing districts, generally to the lesser of 5% or the change in the national Consumer Price Index. It is a limit on a district’s tax extension, not a limit on an individual property assessment or tax bill.

What Illinois Does Not Have

There is no statewide law limiting how much your own property 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.

Which Illinois counties have PTELL?

PTELL applies in Cook County, the collar counties, and counties that adopted it by referendum. The Illinois Department of Revenue’s county map linked above shows where PTELL applies. Its presence in a county does not mean every property tax bill in that county is capped.

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

How much can property taxes increase in Illinois?

There is no fixed statewide maximum increase for an individual Illinois property tax bill. PTELL can limit growth in a covered taxing district’s extension, but your bill can increase much more if your assessment grows faster than other properties or if your bill includes increases outside the ordinary PTELL calculation.

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.

If you own a home in Cook County, the part you can challenge is the assessment. Review your property’s assessed value against comparable properties and file an appeal when the assessment is not fair.

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.