Illinois Property Tax Appeal & Protest Guide (2026)
Calculate your assessment reduction, check the 30 days after publication of assessment list (Cook County operates on rolling township deadlines) statutory deadline, and access county appraisal district e-File portals under 35 ILCS 200/16-55
Illinois Assessment Appeal Standard: Under 35 ILCS 200/16-55, homeowners in Illinois can appeal county real property assessments through the Assessor appeal (Cook County Assessor / Township Assessor) or County Board of Review (BOR). The statutory appeal deadline is 30 days after publication of assessment list (Cook County operates on rolling township deadlines) using form Complaint on Real Property Assessment (Board of Review Form). Protests are evaluated on Lack of uniformity (assessed higher than identical homes in neighborhood) and Market value overstatement based on recent appraisal supported by Uniformity grid showing 3 to 5 PINs with lower assessed value per square foot and Certified appraisal report.
Illinois Property Tax Appeal & Protest Calculator
Governing Law: 35 ILCS 200/16-55 · Annual Deadline: 30 days after publication of assessment list (Cook County operates on rolling township deadlines)
1. Property Assessment & Target Valuation
Enter the preliminary appraised value from your county assessment notice and the realistic fair market value supported by comparable sales.
2. Local Tax Rate & Jurisdiction
Property tax rates are set by combined county, city, ISD, and special hospital/MUD districts.
Reducing your assessed valuation by $55,000 lowers your annual tax liability across all local taxing entities (school district, county, city, hospital).
⚖️ Statutory Protest Stages in Illinois:
- Assessor appeal (Cook County Assessor / Township Assessor)
- County Board of Review (BOR)
- State Property Tax Appeal Board (PTAB) or Circuit Court
COUNTY PROPERTY TAX APPEAL EVIDENCE DOSSIER & HEARING PACKET
JURISDICTION: STATE OF ILLINOIS · STATUTE: 35 ILCS 200/16-55
Target Tax Year: 2026 · Official Protest Instrument: Complaint on Real Property Assessment (Board of Review Form)
Filing Deadline: 30 days after publication of assessment list (Cook County operates on rolling township deadlines)
Prepared: 10/23/2026
| County Preliminary Appraised Value: | $420,000 |
| Claimant Target Market Value (Supported by Comps): | $365,000 |
| Combined Effective Local Tax Rate: | 2.12% |
| Estimated Annual Tax Overcharge Savings: | $1,166 / Year |
1. Comparable Market Sales (Comps) Grid — Valuation Equity Evidence
| Subject Property / Comps | Living Area (Sq Ft) | Sale Date | Sale / Assessed Price | Adjusted Price / Sq Ft |
|---|---|---|---|---|
| Subject Property (County Valuation) | — | Lien Date: Jan 1 | $420,000 | — |
| Comp 1: Same Subdivision / Block | Similar GLA | Past 12 Months | — | — |
| Comp 2: Similar Model / Age | Similar GLA | Past 12 Months | — | — |
| Comp 3: Similar Bed/Bath Count | Similar GLA | Past 12 Months | — | — |
*Attach county deed records, MLS closing settlement statements, or appraisal district property cards for each comparable sale.
2. Itemized Deferred Maintenance & Physical Condition Deductions
| Defect / Condition Issue | Evidence Attached | Estimated Repair Cost |
|---|---|---|
| Roof / Plumbing / Foundation | Contractor written repair estimate + photos | $_______________ |
| HVAC Mechanical End-of-Life | HVAC diagnostic inspection report | $_______________ |
| Negative Externalities (Traffic / Drainage) | Site photos, aerial GIS map, flood zone record | $_______________ |
3. Appraisal Review Board (ARB) 5-Step Hearing Strategy:
- Collate 4 Copies: Hand 1 copy to each of the 3 panel members and 1 copy to the county appraiser.
- Focus on Facts, Not Taxes: State tax boards have zero control over tax rates; frame arguments strictly on Fair Market Value and Uniform Assessment Equity.
- Stick to the Lien Date: Only cite market transactions and physical condition occurring on or before the statutory valuation date.
- Present Contractor Estimates: Unrepaired physical defects must be supported by third-party licensed bids.
- Politely Rebut County Comps: Point out superior upgrades, square footage variances, or busy road differences in county comps.
Property Owner / Appellant Signature:
Printed Name / Executed Under Penalty of False Swearing / Date
County Property Identification / Account #:
Geographic ID / Parcel Number / Subdivision Lot & Block
Major Illinois County Appraisal Districts & e-File Portals
Official appraisal district portals, contact numbers, and filing links for Illinois’s largest metro counties
Cook County
Cook County Assessor & Cook County Board of ReviewCook County divides 38 townships into a 3-year assessment cycle. Lack-of-uniformity appeals have exceptionally high success rates.
Illinois Property Tax Protest Legal Framework
Statutory Authority & Deadlines
Statutory Appeal Stages
- Assessor appeal (Cook County Assessor / Township Assessor)
- County Board of Review (BOR)
- State Property Tax Appeal Board (PTAB) or Circuit Court
Mandatory Evidence Checklist
- Uniformity grid showing 3 to 5 PINs with lower assessed value per square foot
- Certified appraisal report
- Settlement statement if purchased within last 24 months
Protest Benchmarks
Frequently Asked Questions
What is the property tax appeal deadline in Illinois for 2026?
What are the legal grounds for protest in Illinois?
Who carries the burden of proof in a Illinois property tax hearing?
What form must I file to initiate an appeal in Illinois?
What is the historical success rate for residential property protests in Illinois?
Official Standards & Authoritative Sources
Illinois Department of Revenue / Illinois PTAB
Illinois Official Property Tax Rules & Oversight
official-state-agencyReviewed & verified by the RateFig Property Tax & Assessment Editorial Team. Data retrieved October 19, 2026. Estimates are planning aids, not financial advice — see our editorial standards.
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