Property taxes in Illinois are among the highest in the country. While the median value for a home in Cook County is $210,000, the median tax bill is $4,680. This is $2,280 higher than the national median property tax bill. At an effective property tax code rate of 2.01%, Illinois is much higher than the national median of 1.02%. In November 2024, Illinois voters responded "yes" to a tax advisory question asking if Illinois income tax should go up to relieve property taxes, signaling residents are weary of the high costs.
When the county provides your property tax bill, the total amount is calculated based on the assessed value of your home. If you feel that the amount is high, you can appeal it through a simple process.
Understand the Property Tax Appeal Process
Illinois releases property valuations at different times throughout the state. One-third of properties (except farmland) are assessed each year to determine Cook County property taxes. Most property owners receive a current assessment every three years, although you can appeal during off years, too.
Cook County is home to more than five million people and 134 municipalities. With a complex tax system, the county relies on triennial reassessments. There are more than 1.8 million parcels of land divided into three sections:
City of Chicago: Property reassessed in 2024 and 2027
North Suburbs: Reassessed in 2022 and 2025
South and Western Suburbs: Reassessed in 2023 and 2026
Register Your Intent to Appeal With the County
As the most populous county in Illinois, Cook County has a different process from the rest of the state. Here's both the Cook County and state requirements:
Notify the Cook County assessor that you plan to appeal your property's valuation. You can also notify the Cook County Board of Review. The county's stringent timeline only allows a 30-business-day appeal window.
Outside Cook County, you must only contact your chief county assessment officer or the local assessor and let them know you plan to appeal your property valuation. Some may require a complaint form or written notice, but you must make a formal appeal to your local county board.
You can find more information about how to register your intent to appeal with the Illinois Property Tax Appeal Board (PTAB). The PTAB has five members, all appointed by the governor with the State Senate's advice and consent.
Missing a deadline may disqualify you from filing an appeal. Timelines differ throughout the state, so check with your local county assessor's office as soon as you receive your notice so you understand the due dates.
Gather Evidence To Support Your Appeal
Once you've filed an appeal with the county, the next step is to gather evidence supporting your claim that your taxable property's valuation is wrong. You have several ways to do this:
A copy of the property record card, along with photographs of your property
Comparable sales reports with photos of similar properties in your neighborhood
An official appraisal of the subject property
Property record cards for similar properties in the area, along with photographs
A copy of the contract for purchase, deed, or Real Estate Transfer Declaration.
The more evidence you have, the more likely your appeal is to be successful.
Conduct a Thorough Review of Your Property Tax Assessment
Before filing an appeal, make sure you understand your property tax assessment and notice. For tax purposes and because of a 1975 law, the property is assessed at 33.33% of its market value. After the assessor has determined the market value, they apply the percentage to figure out the tax amount.
You may also qualify for property tax exemptions in Illinois if it's a residential property. The general homestead exemption reduces the value of your property on paper without lowering its market value. Check for any exemptions you're eligible for.
Pay close attention to the property details and legal description. Check physical attributes, number of rooms, and square footage. The state of the real estate market can artificially affect your property value. Check your assessment notice for any discrepancies or errors before filing an appeal.
Document any Property Improvements or Damage
The county assessor probably hasn't even seen your property. If there's any damage or improvements to your property, document them. For example, if shingles blew off in a recent storm and your roof is unstable, that could decrease the assessed value of your home and help your assessment appeal.
Engage With County Officials During the Process
Most county officials want to work with you to keep the process quick and accurate. In most cases, there's no formal hearing, but you will meet with the review board. In some cases, you can come to an agreement with the assessor without the help of the entire board.
Prepare for the Hearing: What To Expect
Once the board of review has met with you, it will decide by majority vote. This decision is based on the evidence you present, which is why it's crucial that it's accurate and thorough.
Present Your Case Effectively at the Hearing
The most important thing you can do at the hearing is come prepared. Be ready to defend your assessment of your property's value, not through feelings but through evidence. If you aren't happy with the board's final decision, you have one more chance: appealing to the Property Tax Appeal Board.
Timelines and Deadlines for Appeals
Deadlines vary by county. Contact your assessor's office to verify the dates, but here is a basic overview of the timeline:
Assessments are usually sent out in the spring or early summer (May or June in Cook County).
The Board of Review offers a
30-day
window to file an appeal.
Most counties hold hearings and appeals in late summer or early fall (July through September in Cook County).
The Local Board of Review responds within several weeks to a few months.
Visit your county's website to stay current on its exact timelines. Also, watch out for mail notices or any information from the board!
Common Mistakes To Avoid During the Appeal Process
Don't show up without enough evidence to prove your claim. Collect comparable sales data, have an independent appraisal done, document property issues, and highlight any mistakes made on the assessment.
When appealing, focus on the property value, not the tax bill. The tax bill will decrease if the property value decreases, but the board is there to discuss the home's value.
Additional Resources for Illinois Property Owners
Illinois property owners may qualify for exemptions that decrease the property's value and lower the tax bill. Rely on your local assessor's website, information from the Illinois Department of Revenue, and the State of Illinois Property Tax Appeal Board. If you want to maximize your savings without a hassle, Ownwell offers local tax experts combined with specialized software to make sure you take advantage of every tax break you deserve.
Use Ownwell To Get the Largest Tax Reduction
At Ownwell, we want to help you save money. We understand property valuations, assessments, and appeals. Allow us to help you maximize your tax savings — and remember, you don't pay unless we lower your tax bill.
Our process does all the work for you to receive a successful appeal in Cook County, Illinois.
