Cook County property taxes have been on the rise for over three consecutive decades. Illinois now ranks among the states with the highest property taxes in the nation and, by some measures, has surpassed New Jersey in effective residential property tax rates. While some important reforms have taken place, including an overhaul of the tax sale system, there is a long way to go. With little legislative support coming now or in the future, it falls to the people of Cook County to take their destiny into their own hands. While exemptions are a good start, a record number of people are filing property tax appeals.
While much of Illinois was wrapped up in the saga of the Chicago Bears, some key deadlines have been going on in the background. While the Bears and the government may be in a showdown, the people of Cook County have been receiving their notices of reassessment.This opens the door for assessor appeals, which are protests filed directly with the Cook County Assessor’s Office (CCAO). Taxpayers generally have 30 business days to file an appeal after receiving their assessment notice, which means that many townships have already reached the end of this first stretch. October is an important month for a few prominent townships in Cook County.
Appeals are a Necessity in Cook County
Appeals are a challenge to the market values assessed by the CCAO. These are used as the first number in the long calculation to determine tax bills. The market value has the assessment ratio and equalization factor applied to it to create the equalized assessed value (EAV), which can then be multiplied by various tax rates. By appealing the market value, a taxpayer can see a reduction in their taxes after the whole formula is run. Notably, this is applied before exemptions, meaning that both can be used at once to maximize savings. Exemptions are generally applied to the EAV.
The goal of appeals is to correct any errors that are generated by the CCAO’s assessment process. They are generally targeted at overassessment, where the market value is higher than what the real estate market actually is, and a lack of uniformity in assessment, where a property is assessed higher than its peers. In general, challenging the values of the CCAO means taking a second look and catching any errors before they become permanent. Due to rising costs, tax rates, and equalization factors, getting the values right should be the top priority of every property owner in Cook County.
Assessor Appeals are a Unique First Step
Cook is the only county in Illinois that has official assessor appeals. While other counties do see taxpayers make unofficial pleas to their assessor, Cook is the only one where these protests are official, with their own deadline and rules. The assessor appeal is the first option that taxpayers have when it comes to challenging their values. If there is no settlement offered by the CCAO, or it is too low, then the taxpayer can file a formal appeal with the Board of Review (BOR). In the rest of the state, every township has only a single deadline, which is based on the BOR. This gives the people of Cook County an extra opportunity to land a reduction.
A Tight Window
Assessor appeals are based on township, meaning there are 38 separate deadlines across the county. The appeal window remains open for 30 business days after the notice of assessment is published. Each township is generally staggered a week apart, though there is some margin for error. As notices are published, the window for assessor appeals opens and closes with each township, going in order. For instance, Calumet Township published its notices on August 20, which means that the deadline to appeal will be October 2. For an appeal to be successful, a taxpayer must gather the evidence needed within the window, as this is the most vital part of the process.
Current Assessor Deadlines
Closed for Assessor Appeals
- Barrington
- Berwyn
- Bremen
- Cicero
- Cicero
- Elk Grove
- Evanston
- Lakeview
- Lemont
- Lyons
- Maine
- New Trier
- Northfield
- Norwood Park
- Oak Park
- Palos
- River Forest
- Riverside
- Rogers Park
- Stickney
- West Chicago
BOR Appeals Later in the Year
While assessor appeals are the first step, they are not the only option. BOR appeals are scheduled for much later in the year, which gives taxpayers a much longer time to gather evidence. Both businesses and homeowners have seen strong results when appealing to the BOR, so if you missed the deadline for the assessor, you still have an opportunity later in the year. BOR appeals are held between August and November, though there can be special extensions, such as the short December window that was opened in 2025.
Evidence Required
While it is different from a hearing with the BOR, an assessor appeal uses the same evidence. To prove that a home or business is overassessed, sales data from comparable properties can help demonstrate that a property’s assessed value exceeds market value. This can show that the market value of your property does not match that of the open market. When it comes to showing a lack of uniformity, a collection of assessments in the same area needs to be shown so that it can be demonstrated that your property is being assessed unequally compared with neighboring properties. In order for these comparisons to be valid, the properties must be in the same location, around the same age, and be of a similar size. The better the evidence gathered, the better shot you have at a reduction, no matter what level you decide to appeal to.
O’Connor Assists with Evidence and Analysis
If you are considering an appeal, but the required evidence is overwhelming, we at O’Connor are here to help. For over 50 years, we have given aid to taxpayers looking to lower their taxes through appeals. When you join us, you will be given a client success consultant who acts as your personal guide and consistent point of contact. They will get to know your case and act as a liaison between you and the experts who are gathering evidence for you. You will always have the same person to call or email, ensuring that you are always up to date with your case.
When you sign up with us, we will analyze your assessment and then use data-driven techniques to find the exact evidence required to make your case. We will then consult our advanced databases, which will let us find the perfect sales records and assessment comparisons to show that your home or business is overvalued. Once all of the evidence is put together and organized in a professional manner, we will coordinate an appeal with Kieta Law. This means that you will have both expert representation and the evidence to back it up. There is no upfront cost for us to gather evidence or do analysis, and you will only need to pay a portion of your winnings if you and your attorney are able to lower your taxes.
