How to Appeal Your Property Tax in Illinois
Illinois homeowners can appeal their property tax assessment if they believe it's too high. This guide covers the 2026 appeal deadline, required evidence, and step-by-step process.
How Illinois Assesses Property
Illinois assesses residential property at 33.33% of market value. This means if your home is worth $239,000, your assessed value would be $79,659.
Illinois assesses residential property at 33.33% of fair market value statewide. Cook County uses a 10% ratio for residential under its classification system.
The Appeal Process
Appeals are heard by the Board of Review. An informal review is available before filing a formal appeal.
County Assessor (Informal)
Board of Review
Property Tax Appeal Board (PTAB)
Circuit Court
Illinois Appeal Deadline
What Overassessment Costs Illinois Homeowners
The median home in Illinois is worth $239,000. If your assessment is just 10% too high, you may be overpaying:
~$495/year
Effective tax rate: 2.07% · Median value: $239,000
Check Your Illinois Assessment
Enter your address to see your estimated overassessment and Illinois filing deadline.
Illinois Counties
Champaign County
Median: $205,100 · Rate: 2.07%
Deadline: July 1 through September 10, 2026
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Cook County
Median: $335,800 · Rate: 1.89%
Deadline: 30 days after receiving your reassessment notice
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DeKalb County
Median: $247,000 · Rate: 2.22%
Deadline: 30 days from the publication date of the assessment notice for your township
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DuPage County
Median: $409,100 · Rate: 1.91%
Deadline: 30 days after publication of township assessment roll
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Grundy County
Median: $193,300 · Rate: 2.61%
Deadline: Varies by township; typically late November (for 2025 tax year, many townships had November 27, 2025 deadline)
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Kane County
Median: $312,600 · Rate: 2.60%
Deadline: 30 calendar days after date of publication of the current year assessment list
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Kankakee County
Median: $180,250 · Rate: 2.4%
Deadline: 30 days after receiving the assessment notice in the fall
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Kendall County
Median: $257,000 · Rate: 2.83%
Deadline: 30 days from assessment notice publication date
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Lake County
Median: $287,300 · Rate: 2.94%
Deadline: 30-day deadline from the date of publication
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LaSalle County
Median: $125,500 · Rate: 2.10%
Deadline: 30 days from publication date for your township, or December 1, 2025 for all 2025 assessments
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Macon County
Median: $121,800 · Rate: 2.10%
Deadline: 30 days from publication date in local newspaper
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Madison County
Median: $128,300 · Rate: 1.75%
Deadline: 30 days from the publication date for your township
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McHenry County
Median: $328,900 · Rate: 2.18%
Deadline: 30 days after the publication of your assessment
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McLean County
Median: $163,629 · Rate: 2.62%
Deadline: 30 days after the publication date for your township
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Peoria County
Median: $119,000 · Rate: 2.0%
Deadline: 30 days from the date of publication in the local newspaper for each township
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Rock Island County
Median: $111,700 · Rate: 2.01%
Deadline: 30 days from the date assessment changes are published in the newspaper
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Sangamon County
Median: $118,900 · Rate: 1.87%
Deadline: 30 days after the date of publication of township assessment changes
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St. Clair County
Median: $122,400 · Rate: 1.87%
Deadline: 30 days from the date assessment notices are published or mailed
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Tazewell County
Median: $125,700 · Rate: 1.85%
Deadline: September 19, 2025 for 2024 assessment year; typically late September annually or 30 days from published notice
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Will County
Median: $240,500 · Rate: 2.05%
Deadline: 30 calendar days from the date of notice
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Winnebago County
Median: $119,208 · Rate: 2.78%
Deadline: 30 calendar days after assessments are published
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Key Terms for Illinois Homeowners
The percentage of a property's market value that a state uses to calculate the assessed value for property tax purposes.
An optional first step in the appeal process where a property owner discusses their assessment directly with the assessor's office before filing a formal appeal.
Illinois Guides & Resources
📋 Property Tax Appeal Deadlines by State: The Complete 2026 Calendar
Filing windows for all 50 states
📋 Cook County Property Tax Appeal Guide (2026)
Chicago-area triennial assessment guide
📋 How to Appeal Property Taxes in Illinois: Complete 2026 Guide
Complete guide with deadlines, forms, and step-by-step instructions
📋 How Much Can Property Taxes Increase in Illinois? (PTELL Explained)
PTELL limits levies, not individual bills
📅 Illinois Property Tax Appeal Deadlines 2026: Cook County & Beyond
Illinois filing deadlines and process
🏦 How to Appeal Property Taxes in Escrow in Illinois (2026)
Yes, you can appeal even if your lender pays your taxes
🔑 Inheriting Property in Illinois: What Happens to Property Taxes (2026)
Illinois reassessment rules, exemptions, and strategies for inherited property
👤 Illinois Senior Property Tax Benefits: Every Exemption, Freeze & Deferral (2026)
Age 65+ exemptions, freezes, and deferrals in Illinois
Average Property Tax Rate by State (2026 Data)
National average is 1.1%. Where does your state rank?
Average Property Taxes by State 2026: Complete Rankings & What You Actually Pay
Average Property Taxes by State 2026
Property Tax Appeal Success Rates by State: 2026 Data & Analysis
Property Tax Appeal Success Rates by State
Property Tax Appeal Success Rates: Real Data by State and County (2026)
National average is 40-60%. See state-by-state data.
Property Tax Appeal Statistics: Success Rates, Savings & Data (2026)
Success rates, savings, and outcomes
Property Tax Appeal Success Rates: What the Data Shows
What the data shows about win rates
Every Property Tax Exemption by State: Senior, Veteran, Homestead & Disability (2026)
Homestead, senior, veteran, disability exemptions for all 50 states
Senior Property Tax Exemptions by State: The Complete 2026 Guide
Age-based discounts in every state
Best Ways to Lower Your Property Taxes (2026): 9 Methods That Work
9 methods that work in 2026
Property Tax Exemptions Guide: 8 Types That Could Save You Thousands (2026)
8 types that could save you thousands
How to Lower Property Taxes Without Filing an Appeal
Exemptions and programs that don't require filing
How to Appeal Property Taxes as a Senior
Age-specific strategies and exemptions
2026 Property Tax Increases: What Homeowners Need to Know
Why assessments are surging and how to respond
Senior Property Tax Freeze vs Appeal: Which Saves More Money?
Senior Property Tax Freeze vs Appeal
Illinois Homestead Exemption 2026: Save $800 Every Year (Most Homeowners Missing Out)
Illinois's homestead exemption can save you $800 annually. H
What Evidence Do I Need for a Property Tax Appeal? (2026)
Comparable sales, photos, and assessment errors
How to Appeal Your Property Taxes: The Complete Guide (2026)
Step-by-step from notice to hearing
Can Appealing Your Property Taxes Actually Raise Them? Here's the Truth
The #1 fear and what actually happens
Property Tax Appeal Letter Template: How to Write a Winning Appeal (2026)
Copy, customize, and send in 15 minutes
What Happens at a Property Tax Appeal Hearing (And How to Prepare)
What to expect and how to prepare
How Much Does a Property Tax Appeal Cost?
DIY, flat-fee, and contingency options
How to Find Comparable Sales for Your Property Tax Appeal
Where to find comps and what makes them strong
How Long Does a Property Tax Appeal Take? Timeline by State
Timeline from filing to decision
What Is the Best Evidence to Protest Property Taxes? Expert Guide (2026)
Recent comparable sales carry the most weight, but combining multiple evidence types increases success.
How to Appeal Property Taxes Without a Lawyer (And When You Might Need One)
DIY vs. hiring a professional
How to Appeal Property Taxes Without an Appraisal: Use Comps Instead
Comps vs. formal appraisals
How to Appeal Property Taxes Without Going to a Hearing
Mail, online, and phone appeal options
How Property Tax Assessments Work: The Complete Guide to Understanding Your Tax Bill
How Property Tax Assessments Work
What Does a Property Tax Appeal Evidence Packet Look Like?
What Does a Property Tax Appeal Evidence Packet...
Property Tax Appeal Strategies for New Homeowners: First-Year Assessment Challenges
Why your first tax bill is often too high — and how to fix it
Mass Appraisal Limitations: How They Lead to Inaccurate Property Taxes
7 flaws in how your county values your home — and how to use them
Is It Worth It to Appeal Property Taxes? (2026 Analysis)
Average savings: $1,100/year
Understanding Your Property Assessment Notice: What Every Homeowner Should Know
What that notice means and what to do next
First-Time Homebuyer's Guide to Property Taxes
What new homeowners need to know
How to Read Your Property Tax Bill
Understanding the numbers and where to look
Is My Property Overassessed? How to Tell
How to tell if you're paying too much
When Should I File My Property Tax Appeal? Critical Deadlines by State (2026)
State-specific deadlines and optimal filing strategies to maximize your chances.
You Just Got Your Property Assessment Notice: Here's Exactly What to Do Next
What to do when your assessment arrives
First-Time Property Tax Appeal: A Beginner's Guide
First
Inherited Property Tax Appeal: Step-by-Step Guide for 2026
Inherited Property Tax Appeal
Is My Property Over-Assessed? 5 Signs You're Overpaying
Is My Property Over
Best Property Tax Appeal Services in 2026: Pricing, Coverage, and What to Know
Pricing, coverage, and what to know
Best DIY Property Tax Appeal Tools & Resources (2026)
Free and paid tools for self-filers
Ownwell Review 2026: Pricing, Results & Is the Fee Worth It?
Pricing, success rates, $50M funding, and cheaper alternatives
How a Woodstock, IL Homeowner Saved $2,831/Year on Property Taxes
Real data: 37.3% overassessment, $2,831/year in excess taxes
Property Tax Appeal After Renovation: What You Need to Know in 2026
When upgrades trigger reassessment
Property Tax Appeals for Investment Properties
Different rules for rentals and commercial
What Happens If You Don't Pay Property Taxes?
Liens, penalties, and how to avoid them
How to Appeal Property Taxes After a Home Renovation: Avoid Over-Assessment
Why renovation cost doesn't equal taxable value — and how to prove it
How Do I Appeal My Property Taxes Myself? Complete DIY Guide
Complete step-by-step instructions
Are Property Tax Protest Companies Worth It? Cost vs. Savings Analysis
Contingency fees vs. flat-fee vs. DIY
What to Write When Protesting Property Taxes: Examples & Templates
Winning phrases and examples
Commercial Property Tax Appeal Strategies That Work in 2026
Commercial Property Tax Appeal Strategies That ...
Property Tax Appeal Resources
Best Appeal Services Compared
7 companies compared — pricing, coverage, and pros/cons for 2026.
2026 Appeal Deadlines
Every state's deadline, filing method, and what happens if you miss it.
Assessment Ratios by State
Every state's assessment percentage — from 4% to 100% — with worked examples.
9 Ways to Lower Your Property Taxes
From homestead exemptions to formal appeals — every method that works.
Savings Calculator
Check if you're overassessed — enter your assessed value to see potential savings.
Flat Fee vs Contingency: Which Saves More?
$49 flat vs 25-50% of savings — see the break-even math at every savings level.
Frequently Asked Questions
How do I appeal my property tax in Illinois?
When can I appeal my property tax in Illinois?
What is Illinois's property tax assessment ratio?
How much can I save by appealing in Illinois?
What evidence do I need for a Illinois property tax appeal?
What is the effective property tax rate in Illinois?
Can I file a Illinois property tax appeal online?
Ready to Appeal Your Illinois Property Tax?
Enter your address for a free overassessment analysis. If the numbers support a appeal, your complete evidence packet is $49.