Illinois Property Tax Appeal Guide
Illinois assesses most property at 33.33% of fair market value (Cook County uses a 10% residential classification), so appeals target market value and uniformity.
33%
Statutory percentage
30 days from assessment notice (varies by township)
Verified July 2026 — confirm on your notice
35 ILCS 200/16-55 (board of review); Cook County classification ordinance
Governing state code
How to File in Illinois
Check your township's assessment publication date and current assessed value.
File an appeal with the county assessor during your township's open appeal window.
Submit comparable sales or lack-of-uniformity evidence with the appeal.
If denied, appeal to the county Board of Review within 30 days of publication.
Escalate to the Illinois Property Tax Appeal Board (PTAB) or circuit court.
Deadlines and ratios vary by county and change over time — always confirm with your local assessor. This is general information, not legal advice.
Are you actually over-assessed in Illinois?
Check this property against recent comparable sales for $4.99. If the evidence says you have no case, you know that before you spend a filing deadline on it — and if it does, the same $4.99 is credited toward the full appeal packet.
Illinois County Guides
County-specific deadlines, forms, assessor contacts, and filing steps.
A worked example in Illinois
Say the assessor values your home at $400,000, but comparable sales show it is really worth $350,000 — a $50,000 over-assessment. Illinois taxes 33% of value, so the taxable amount drops from $133,320 to $116,655. At a typical effective rate of ~1.5%, that is about $250 back in your pocket every year until the value is corrected.
Illustration only. Your actual rate, exemptions, and savings depend on your county and taxing districts — run your own numbers.
Common grounds for a Illinois appeal
Over-market valuation. Comparable sales of similar nearby homes closed below the value the assessor placed on yours.
Errors in the property record. The county has the wrong square footage, bedroom or bathroom count, lot size, or condition on file.
Unequal (non-uniform) assessment. Comparable properties in your area are assessed for less than yours, regardless of market value.
Physical or external problems. Deferred maintenance, functional issues, or an external nuisance depress what a buyer would pay.
Overvaluation · Unequal assessment · Incorrect classification · Denial of exemption
Don’t overlook exemptions
An appeal lowers your value, but exemptions cut your taxable base directly — and both stack. Most owners qualify for a homestead exemption on their primary residence, and many states add relief for owners over 65, veterans, and people with disabilities. Confirm you are enrolled with your Illinois county assessor before filing — it is the fastest saving most people miss.
- General Homestead Exemption $10,000 EAV reduction
- Owner-occupied primary residence
- Senior Homestead Exemption $8,000 EAV reduction
- Age 65+, owner-occupied
- Senior Assessment Freeze Frozen EAV
- Age 65+, income ≤$75,000 (tax year 2026; $77,000 for 2027, $79,000 from 2028 — Public Act 104-0452)
- Disabled Veterans Exemption Up to $100,000 EAV
- Service-connected disability
Who hears a Illinois appeal
Your appeal is decided by County Board of Review — the value itself is set by the Township/County Assessor, which is who you are disagreeing with.
- 1
Assessor review
- 2
Board of Review
- 3
Property Tax Appeal Board (PTAB)
- 4
Circuit Court
Each stage has its own deadline. Missing the first one usually closes the later ones for that tax year.
Key Illinois statutes
The sections a Illinois appeal is argued under. Quote one exactly as written — a paraphrased or renumbered citation is worse than none.
- 35 ILCS 200/9-145
- Assessment Level
- 35 ILCS 200/16-55
- Board of Review Complaints
- 35 ILCS 200/16-160
- Property Tax Appeal Board
- 35 ILCS 200/15-175
- General Homestead Exemption
- 35 ILCS 200/15-170
- Senior Citizens Homestead Exemption
- 35 ILCS 200/15-172
- Senior Citizens Assessment Freeze
Official Illinois resources
These are state government sites. The form and portal you actually file through are published by your county assessor.
Illinois property tax appeal questions
- When is the deadline to appeal property taxes in Illinois?
- 30 days from assessment notice (varies by township). Verified July 2026. Deadlines vary by county and change from year to year, so always confirm the date printed on your own assessment notice before you file.
- Who decides a property tax appeal in Illinois?
- County Board of Review hears it. The full path is: Assessor review, then Board of Review, then Property Tax Appeal Board (PTAB), then Circuit Court.
- What is the assessment ratio in Illinois?
- 33.33% of fair market value (1/3 of market value). That is the share of value your bill is calculated on, so lowering the assessed value lowers the bill proportionally.
- What grounds can I appeal on in Illinois?
- Illinois recognises these grounds: Overvaluation, Unequal assessment, Incorrect classification, Denial of exemption. Overvaluation is the most common — you show comparable sales that closed below your assessed value.
- What property tax exemptions does Illinois offer?
- General Homestead Exemption — $10,000 EAV reduction, for owner-occupied primary residence; Senior Homestead Exemption — $8,000 EAV reduction, for age 65+, owner-occupied; Senior Assessment Freeze — Frozen EAV, for age 65+, income ≤$75,000 (tax year 2026; $77,000 for 2027, $79,000 from 2028 — Public Act 104-0452); Disabled Veterans Exemption — Up to $100,000 EAV, for service-connected disability. Exemptions reduce your taxable base directly and stack with an appeal, so check both.
- What is the average property tax rate in Illinois?
- About 1.88% of market value per year statewide. Your own rate depends on your county and its taxing districts, so treat this as a benchmark rather than your bill.
Illinois Tax Estimator
$0 / yr
Based on 33% ratio & avg. millage. Estimate only.
Generate your Illinois appeal packet
Check your property for $4.99 (credited), then get the full comparable-sales packet and AI appeal letter for a flat $29 — $19 at launch.