How to Appeal Your Property Taxes in Illinois: Complete Guide

Illinois has the second-highest effective property tax rate in the country. If you own property in Illinois — especially in the Chicago metro area — appealing your assessment is one of the highest-return financial moves you can make. This guide walks you through exactly how to do it.

How Illinois Property Taxes Work

Illinois assesses residential properties at 10% of market value statewide — though Cook County (Chicago) uses a different system with varying assessment levels by property class. Your tax bill is calculated by multiplying your assessed value by your local tax rate, minus any exemptions you qualify for.

Properties are reassessed on a triennial cycle — every three years in most counties, and on a rotating township schedule in Cook County. This means your assessment can jump significantly in a reassessment year, which is exactly when appeals are most valuable.

Exemptions — Claim These First

Before you even think about appealing, make sure you’re getting every exemption you qualify for. Illinois offers several significant ones:

• Homeowner Exemption: Reduces assessed value by $10,000 for your primary residence — apply through your county assessor
• Senior Citizen Exemption: Additional $8,000 reduction for homeowners 65 and older
• Senior Freeze Exemption: Freezes your assessed value if you’re 65+ and meet income limits — extremely valuable in appreciating markets
• Persons with Disabilities Exemption: $2,000 reduction for qualifying homeowners
• Veterans with Disabilities Exemption: Up to 100% exemption for qualifying veterans

Many homeowners leave thousands on the table by not claiming exemptions they qualify for. Check with your county assessor’s office — most exemptions require an annual or one-time application.

Filing Deadlines

Illinois appeal deadlines vary by county and reassessment cycle. General rules:

• Assessor level: 30 days from the date your assessment notice is mailed
• Board of Review: Deadlines vary — Cook County publishes township-specific deadlines; downstate counties typically hold appeals in the fall
• Property Tax Appeal Board (PTAB): 30 days after the Board of Review decision

In Cook County, watch for your township’s reassessment year specifically — that’s when values jump most and appeals are most productive. Check the Cook County Assessor’s website for the current township schedule.

Step-by-Step: The Illinois Appeal Process

Step 1: File with Your Local Assessor

Most counties allow an initial appeal directly with the township or county assessor within 30 days of receiving your notice. This is the fastest and least formal step — bring comparable sales and any evidence of overvaluation. Many straightforward cases are corrected here.

Step 2: Appeal to the Board of Review

If the assessor doesn’t correct the value, file with your county’s Board of Review. In Cook County this is a formal process with specific filing requirements — you’ll submit a complaint form, comparable sales, and potentially a property record card showing errors. Other counties have a similar process but are typically less formal.

Step 3: Property Tax Appeal Board (PTAB)

If you’re still not satisfied after the Board of Review, you can escalate to the state-level Property Tax Appeal Board. PTAB hears cases for all property types across Illinois. The process is more formal — you’ll need to submit a complete evidence packet including a licensed appraisal for most residential cases. Filing fee is $5–$50 depending on property type.

Step 4: Circuit Court

The final appeal option is circuit court — typically only pursued for commercial properties or cases where very significant money is at stake, as it requires an attorney and a licensed appraiser.

Cook County Specifics

Cook County is its own world. A few things specific to Chicago and suburbs:

• The Assessor’s Office (cookcountyassessor.com) has an online appeal portal — most residential appeals can be filed entirely online
• Cook County uses a triennial reassessment rotating through three groups of townships — your township’s reassessment year is when appeals matter most
• Comparable sales must be from the same township and within the prior year for the strongest case
• The Cook County Board of Review (cookcountyboardofreview.com) handles second-level appeals
• Illinois has a specific “equity” argument — if similar properties in your area are assessed lower, you’re entitled to the same treatment even if your market value assessment is technically correct

Best Evidence for an Illinois Appeal

• Comparable sales: 3–5 recent closed sales of similar properties in the same township, same property class
• Equity comps: Similar properties in your area assessed at a lower rate — the equity argument is powerful and unique to Illinois
• Licensed appraisal: Required for PTAB; strongly recommended for Board of Review if significant savings are at stake
• Property record card errors: Square footage errors, bedroom/bathroom count errors, or incorrect lot size — request your property record card from the assessor and check every field

More State Appeal Guides

• California Property Tax Appeal Guide
• Texas Property Tax Protest Guide
• Florida Property Tax Appeal Guide
• New York Property Tax Appeal Guide
• Illinois Property Tax Appeal Guide