Illinois Property Tax Appeal Guide
How to challenge your property tax assessment in Illinois - deadlines, process, and a savings calculator.
What This Data Tells Us About Appeals in Illinois
- Administrative filing in Illinois is listed at $0, so the first barrier is evidence and timing, not a petition fee.
- This ACS extract does not store how often Illinois assessments are reduced on appeal; comparable sales and property-record errors are the evidence the named board typically asks for.
- The typical window centers on August; confirm the current county notice date before relying on the statewide summary. Compare Arkansas's August window before assuming Illinois is early or late.
Primary signal
The administrative filing is usually free
File with the County Board of Review. The reported filing-fee structure is $0; later court or tribunal stages may use a different schedule.
Decision signal 2
Illinois's process has its own procedural details
Cook County (Chicago) has its own Board of Review with specific deadlines by township. Illinois assesses at 33.33% of fair market value.
Decision signal 3
This extract does not store an appeal-win rate
The ACS county medians on this site do not include how often Illinois assessments are reduced on appeal. Recent comparable sales and documented property-record errors are the evidence boards typically ask for.
Decision signal 4
The filing window centers on August
30 days after the publication of the assessment list (varies by county, typically summer). Deadlines can vary by county and assessment cycle, so confirm the current date with the local assessor before relying on this guide.
How to read this guide and disclaimer
Use the ranked signals above as a preparation order, not as a forecast. Start with the filing window and named appeal body because a strong valuation argument cannot cure a missed deadline or a filing sent to the wrong office. Then compare the assessment with recent, genuinely similar properties and document factual errors such as incorrect square footage, condition, or classification.
An estimated success rate is not part of this ACS extract. Keep copies of the assessment notice, evidence, forms, delivery confirmation, and every response from the taxing authority. If a state rule and a county instruction differ, follow the current instruction issued by the office that will hear the appeal.
This guide is for informational purposes only and is not legal or tax advice. Deadlines, filing fees, and procedures vary by county within Illinois and can change year to year. Always verify the current rules with your local assessor's office, or a licensed attorney or tax professional, before filing. Source: Illinois Department of Revenue.
Appeal calendars beside Illinois
Other state boards, not geography. Use them to see whether Illinois's August window is unusual; start with Arkansas and Louisiana.
| Peer state | Typical month | Filing fee |
|---|---|---|
| Arkansas Also open Arkansas appeal steps | August | $0 |
| Louisiana Also open Louisiana appeal steps | August | $0 |
| Pennsylvania Also open Pennsylvania appeal steps | August | $0–$25 (varies by county) |
| Mississippi Also open Mississippi appeal steps | September | $0 |
| Utah Also open Utah appeal steps | September | $0 |
Appeal Deadline
30 days after the publication of the assessment list (varies by county, typically summer)
Appeal Body: County Board of Review
Step-by-Step Appeal Process
- 1
Review your assessment from the township assessor
- 2
File an appeal with the County Board of Review within 30 days of publication
- 3
Submit evidence: comparable sales, independent appraisal, or property data errors
- 4
Attend or submit a written appeal to the Board
- 5
If denied, appeal to the Illinois Property Tax Appeal Board (PTAB) or Circuit Court
Illinois-Specific Notes
Cook County (Chicago) has its own Board of Review with specific deadlines by township. Illinois assesses at 33.33% of fair market value.
Source: Illinois Department of Revenue
Estimate appeal savings
After you have Illinois's deadline (August) and filing route (County Board of Review), project annual savings if an assessment cut sticks. The shared estimator lives on one tools URL so each state page keeps its own process facts instead of reprinting the same form.
Open appeal savings estimator →