Rob Hartley

Founder, AppealDesk · February 27, 2026

How Much Can Property Taxes Increase in Illinois? (PTELL Explained)

Updated February 2026 · 12 min read

Illinois property taxes can increase by much more than 5% per year—even with PTELL. The Property Tax Extension Limitation Law (PTELL) limits how much total revenue taxing districts can collect (5% or CPI, whichever is less), but it does not cap individual property tax bills. Your bill can increase 10%, 20%, or even 50% in a single year due to reassessments, tax burden shifts, and other factors.

This is one of the most misunderstood aspects of Illinois property taxes. Homeowners often assume "5% tax cap" means their bill can't increase more than 5% annually—but that's not how PTELL works. If your property's assessed value increases during a triennial reassessment, or if your neighborhood appreciates faster than the county average, your bill will increase significantly regardless of PTELL limits.

The Bottom Line: PTELL Limits Levies, Not Individual Bills

Here's what you need to know about Illinois property tax increases:

• PTELL limits levy growth to 5% or CPI (whichever is less): This applies to the total amount a taxing district can collect, not individual property bills.
• Individual bills are NOT capped: Your property tax bill can increase by any amount if your assessed value rises during reassessments.
• Triennial reassessments drive volatility: Illinois reassesses all properties every three years, causing significant bill fluctuations.
• Home rule municipalities are exempt: Cities like Chicago can raise property taxes without PTELL limits.
• Tax burden shifts: Even with PTELL, if your property's value increases faster than your neighbors', you'll pay a larger share of the capped levy.

Translation: PTELL provides modest protection against runaway government spending, but it does NOT protect homeowners from large tax bill increases. If you want to limit your property tax increases in Illinois, appealing your assessment is your most powerful tool.

What Is PTELL? How the Property Tax Extension Limitation Law Works

The Property Tax Extension Limitation Law (PTELL) was enacted in 1991 to limit property tax growth in Illinois. Despite being commonly called a "tax cap," PTELL is actually a levy limit—it restricts how much total revenue taxing districts can collect, not how much individual property owners pay.

How PTELL Limits Work

• Annual levy growth limited to 5% or CPI (whichever is less): Non-home rule taxing districts can only increase their total property tax extension (the total amount billed to all properties) by this amount each year.
• New construction excluded: PTELL allows additional revenue from new construction, additions, and improvements—these don't count toward the 5%/CPI limit.
• Voter-approved increases exempt: Referendums can authorize levy increases beyond PTELL limits (for schools, libraries, parks, etc.).
• Home rule municipalities exempt: Cities like Chicago, Evanston, and other home rule jurisdictions can raise property taxes without PTELL restrictions.

Example of how PTELL works:

• Township School District collected $10 million in property taxes in 2025
• CPI for 2026 is 3.2%, PTELL limit is 3.2% (less than 5%)
• District can collect up to $10,320,000 in 2026 ($10M x 1.032)
• Plus additional revenue from new construction (no limit)
• Plus voter-approved increases (if any)

Why PTELL Doesn't Protect Your Individual Bill

Here's the critical misconception: PTELL limits the total pie, not your slice of it. If the total levy is capped at $10.32 million, but your property's assessed value increases from $300,000 to $400,000 (+33%) during a reassessment, your share of that $10.32 million will increase proportionally—potentially by 33%, not 3.2%.

Real-world scenario:

• Your home was assessed at $300,000 in 2025
• Total county assessed value: $2 billion
• Your share: 0.015% of total assessed value
• School levy (PTELL-capped): $50 million
• Your 2025 school tax: $7,500 (0.015% x $50M)

After 2026 triennial reassessment:

• Your home reassessed at $390,000 (+30%)
• Total county assessed value: $2.2 billion (+10% average)
• Your new share: 0.0177% of total assessed value (increased because you outpaced the average)
• School levy (PTELL-capped): $51.6 million (+3.2% CPI limit)
• Your 2026 school tax: $9,133 (+21.8%, or $1,633 more)

Despite PTELL limiting levy growth to 3.2%, your individual bill increased 21.8% because your property's value grew faster than the county average. This is why PTELL doesn't stop large tax increases—it just prevents taxing districts from collecting more total revenue beyond the cap.

Triennial Reassessments: The Real Driver of Illinois Tax Increases

Illinois law requires triennial (every three years) reassessments of all real property. These reassessments are the primary reason property tax bills fluctuate dramatically in Illinois—far more than PTELL levy limits.

How Illinois Triennial Reassessments Work

• Statewide schedule: Every county reassesses all properties every three years (except Cook County, which uses a rolling three-year cycle by township).
• Market value basis: Assessments are adjusted to reflect current market values, typically at 33.33% of fair market value (except Cook County at various rates).
• Winners and losers: Properties that appreciate faster than the county average see tax increases; properties that lag behind see decreases.
• No individual assessment caps: Unlike California or Florida, Illinois has no limit on how much your individual assessment can increase during a reassessment.

Cook County's Rolling Reassessment System

Cook County (Chicago and suburbs) uses a unique system: Instead of reassessing all properties countywide every three years, Cook divides the county into three regions (City of Chicago, North Suburbs, South Suburbs) and reassesses one region per year on a rolling three-year cycle.

Cook County reassessment schedule:

• Year 1: City of Chicago townships reassessed
• Year 2: North and Northwest suburbs reassessed
• Year 3: South and West suburbs reassessed
• Repeat cycle

This means Cook County homeowners face reassessments every three years, but only one-third of the county is reassessed each year—reducing market volatility but still causing significant bill fluctuations for properties in the reassessment year.

Real-World Example: Chicago Reassessment (2024)

In 2024, Chicago underwent its triennial reassessment. Results varied widely:

• Hot neighborhoods (Logan Square, Pilsen, Bronzeville): Many properties saw 25-40% assessment increases
• Stable neighborhoods (Beverly, Hyde Park): Modest increases of 5-15%
• Declining areas (South Side, West Side): Some saw assessment decreases
• Tax rate adjustment: City reduced effective rates slightly, but not enough to offset assessment increases in appreciating areas
• Result: Thousands of Chicago homeowners saw property tax bills increase 15-35% despite PTELL supposedly capping levy growth at 3-5%

This illustrates the fundamental problem: PTELL controls levies, not individual bills. Reassessments drive tax bill volatility, and PTELL provides zero protection against assessment increases.

Home Rule Municipalities: No PTELL Protection

Illinois home rule municipalities—including Chicago, Evanston, Oak Park, and other cities with populations over 25,000—are exempt from PTELL. These jurisdictions can raise property taxes as much as they want without the 5%/CPI limitation.

Which Illinois Taxing Districts Are Subject to PTELL?

Subject to PTELL:

• School districts (most, but not all)
• Township governments
• County governments (in PTELL counties)
• Park districts
• Library districts
• Fire protection districts
• Non-home rule municipalities

Exempt from PTELL:

• City of Chicago (home rule)
• Other home rule municipalities (Evanston, Oak Park, Rockford, etc.)
• Debt service levies (bond payments)
• Voter-approved increases (referendums)
• Cook County government (has its own levy limits)

In practice, this means Chicago homeowners have virtually no protection against property tax increases. The city can raise rates as needed, and there's no levy cap to restrain growth beyond political pressure.

Which Illinois Counties Have PTELL?

PTELL originally applied only to collar counties (the suburbs around Chicago). It has since expanded but still doesn't cover all Illinois counties.

Current PTELL Coverage

Collar counties (original PTELL counties):

• DuPage County
• Kane County
• Lake County
• McHenry County
• Will County

Other counties with PTELL:

• Counties that opted in via referendum (check with your county clerk)
• Cook County has its own levy limitation system (not technically PTELL, but similar)

Counties WITHOUT PTELL:

• Most downstate Illinois counties
• Rural counties with smaller populations

If you live outside the collar counties, your local taxing districts may not be subject to PTELL at all—meaning levy growth could exceed 5% annually. Check with your county assessor or county clerk to confirm PTELL status.

Real-World Examples: How Much Can Illinois Property Taxes Increase?

Example 1: DuPage County Reassessment (2023)

• Median home assessment increase: 18%
• Hot areas (Naperville, Wheaton): 25-35% increases common
• Levy growth (PTELL-capped): 4.8% (CPI limit)
• Individual tax bill increases: 10-30% depending on property appreciation
• Appeals: Over 50,000 homeowners filed appeals—one of the highest rates ever

Despite PTELL limiting levy growth to 4.8%, individual homeowners saw much larger increases due to reassessments. Properties that appreciated faster than the county average faced double-digit tax increases.

Example 2: Chicago Tax Increases (2015-2025)

As a home rule municipality, Chicago is exempt from PTELL. Here's what happened:

• 2015: Mayor Rahm Emanuel passed record $543 million property tax increase (largest in city history)
• 2016-2020: Annual property tax increases of 3-5% as city phased in the 2015 hike
• 2021-2023: Additional increases to fund pensions and address budget shortfalls
• Result: Average Chicago property tax bill increased ~45% from 2015 to 2025—far exceeding what PTELL would have allowed

This is why home rule exemptions matter. Chicago homeowners faced unlimited tax increases with no levy cap protection—only political pressure on city leaders provided any restraint.

Example 3: Lake County Stable Market (2022)

In years without reassessments or major market swings, PTELL provides more predictable growth:

• Reassessment year: 2021 (triennial cycle)
• 2022 levy growth (PTELL-capped): 3.0% (CPI limit)
• No new reassessments in 2022
• Individual bill increases: 2-4% for most homeowners (close to levy growth rate)

This shows that in non-reassessment years, PTELL can effectively limit tax bill growth for most homeowners. The problem is reassessment years, when individual assessments jump dramatically.

Comparing Illinois to Other States

How does Illinois' PTELL compare to other states' property tax caps?

Illinois ranks below California, Florida, and Texas for homeowner protection. PTELL's levy limits provide more protection than Pennsylvania or New York, but far less than California's Prop 13 or Florida's Save Our Homes.

Illinois Property Tax Rates: Among the Highest in the Nation

Illinois has some of the highest property tax rates in the United States, contributing to the burden on homeowners:

• Median effective property tax rate: ~2.08% (2nd highest nationally, after New Jersey)
• Highest rates: Cook County suburbs (2.5-3.5%), Lake County (2.5-3.0%), DuPage County (2.3-2.8%)
• Chicago rates: 2.0-2.5% depending on neighborhood
• Lowest rates: Downstate rural counties (1.5-2.0%)

Illinois' high property taxes stem from heavy reliance on local property taxes to fund schools, pensions, and municipal services. Weak state funding for schools forces local districts to raise property taxes, and underfunded pensions create additional pressure on municipalities to increase levies.

When Should You Appeal Your Illinois Property Tax Assessment?

Given that PTELL doesn't cap individual bills, appealing your assessment is often the only way to limit property tax increases in Illinois. You should strongly consider appealing if:

• Your assessment increased significantly during a triennial reassessment (15% or more)
• Your assessed value exceeds recent comparable sales in your neighborhood (after adjusting for the assessment ratio)
• Your home has defects, damage, or issues not reflected in the assessment
• Comparable properties are assessed lower than yours despite being similar
• Your neighborhood has declining property values but assessments haven't adjusted

Illinois Appeal Deadlines

Illinois appeal deadlines are strict and vary by county:

• Cook County: 30 days from date of final assessment notice (typically late summer/fall)
• Collar counties: Typically 30 days from mailing of assessment notice
• Downstate counties: Varies—check with your county Board of Review
• Extensions: Rarely granted; file on time or you lose your appeal rights for that year

Illinois' appeal process is county-specific and can be complex, especially in Cook County where the process involves multiple stages (Assessor's Office review, Board of Review, Illinois Property Tax Appeal Board). Many property owners benefit from professional help.

What Can Illinois Property Owners Do?

Given Illinois' weak protections for individual homeowners, here's how to manage property tax increases:

1. Appeal Your Assessment (Especially During Reassessment Years)

Appealing is your most powerful tool. Illinois property owners who appeal successfully reduce their assessments by 10-25% on average, translating to $1,000-$2,500+ in annual savings.

• Gather recent comparable sales data (adjust for assessment ratio—typically 33.33% of market value)
• Document property issues or defects
• Consider hiring a professional (many work on contingency—no savings, no fee)
• File on time—Illinois deadlines are strict

2. Apply for Homestead Exemptions

Illinois offers several homestead exemptions that reduce your assessed value before taxes are calculated:

• General Homestead Exemption: Reduces assessed value by up to $6,000 in Cook County, varies elsewhere
• Senior Citizens Homestead Exemption: Additional reduction for homeowners 65+
• Senior Citizens Assessment Freeze: Freezes assessed value for seniors meeting income limits
• Disabled Persons' Homestead Exemption: Additional reduction for disabled homeowners
• Veterans' Exemption: Reduction for qualifying veterans

These exemptions can save $500-$2,000+ per year. Apply with your county assessor—they're not automatic.

3. Monitor Local Referendums and Vote

PTELL can be bypassed through voter-approved referendums. Pay attention to ballot measures for school bonds, library levies, park district funding, and other tax increases. These referendums can significantly increase your property taxes beyond PTELL limits.

4. Track Reassessment Cycles

Know when your county is scheduled for triennial reassessment. If you're due for reassessment soon:

• Research comparable sales in your neighborhood now
• Document any property issues or defects
• Set aside savings for potential tax increases
• Be prepared to appeal immediately when reassessment notices arrive

5. Consider the Senior Freeze

If you're 65+ and meet income limits (varies by county, typically $65,000 or less), the Senior Citizens Assessment Freeze Homestead Exemption freezes your assessed value at the current level—providing protection similar to California's Prop 13 for qualifying seniors.

This is one of Illinois' strongest property tax protections, but it's income-limited and only available to seniors. If you qualify, apply immediately—it can save thousands per year.

The Bigger Picture: Illinois' Property Tax Crisis

Illinois' property tax problems stem from structural issues beyond PTELL:

• Underfunded pensions: Illinois has one of the worst-funded pension systems in the nation, creating massive pressure on local governments to raise property taxes.
• School funding inequity: Illinois ranks near the bottom nationally for state funding of schools, forcing local districts to rely heavily on property taxes.
• Too many taxing districts: Illinois has over 6,900 local taxing districts—more than any other state—creating administrative bloat and overlapping levies.
• Political gridlock: Proposals for property tax reform (including assessment caps) have repeatedly failed in Springfield due to concerns about shifting tax burdens or reducing revenue.

Until Illinois addresses these structural issues—through pension reform, consolidated taxing districts, or increased state funding for schools—homeowners will continue to face high property taxes with limited protection from PTELL.

Frequently Asked Questions

Can my Illinois property taxes go down?

Yes, if your property's assessed value decreases during a reassessment (due to declining market values, neighborhood conditions, or successful appeal), your tax bill will decrease proportionally. However, this is less common than increases—most Illinois property values have appreciated significantly over the past decade.

What is the Truth in Taxation law in Illinois?

The Truth in Taxation law requires taxing districts to hold public hearings before increasing their levy by more than 5% or the CPI increase (whichever is less). It's a transparency measure, not a cap—districts can still raise taxes after the hearing, but homeowners have the opportunity to voice objections.

How do I calculate my Illinois property tax?

Illinois property tax is calculated as: (Assessed Value ÷ Assessment Ratio) × Total Levy Rate. The assessment ratio is typically 33.33% of market value (except Cook County, which uses different ratios for residential, commercial, and industrial properties). The levy rate is the combined rate of all overlapping taxing districts (schools, township, county, parks, library, etc.).

Does PTELL apply to Cook County?

Cook County has its own levy limitation system separate from PTELL, but it functions similarly—capping levy growth for non-home rule districts. However, the City of Chicago (home rule) is exempt and can raise taxes without Cook County levy limits.

Can I appeal my property taxes in Illinois every year?

You can file an appeal each year, but most successful appeals occur during or shortly after triennial reassessments when assessments are most likely to be inaccurate. Appeals based solely on "my taxes are too high" rarely succeed—you need evidence that your assessment is incorrect relative to comparable properties.

Final Thoughts: Appeal Is Your Best Defense

Illinois' PTELL provides modest protection against runaway levy growth, but it does nothing to cap individual property tax bills. If your home appreciates faster than the county average during a triennial reassessment, your bill will increase significantly—regardless of PTELL limits.

The average successful appeal in Illinois reduces assessments by 10-20%, saving homeowners $1,200-$2,000+ per year. Over a decade, that's $12,000-$20,000+ in savings—more than enough to justify the time and effort required to appeal.

If your property tax bill increased significantly after a recent reassessment, don't assume it's accurate. Get a professional assessment review, gather comparable sales data, and file an appeal. In Illinois, where PTELL doesn't protect individual bills, appealing is often the only way to keep your property taxes under control.