I own a two-flat in Humboldt Park with taxes that, for years, seemed suspiciously low. Low enough that I didn't want to draw attention to it. My honest fear was that filing an appeal would put my property in front of someone at the county who would take a look, realize the number was wrong in my favor, and fix it.
I appealed anyway. Nothing went up.
That was my particular hangup, but might not be the most common one. What I run into far more often is homeowners who have never considered appealing at all. They treat the number on the bill the way they treat the number on a water bill: that's what it costs, and there's nothing to be done. There is something to be done, it's free to attempt, and most people never try.
When the second installment bills landed this month, I called a paralegal at the property tax law firm that handles my appeals and asked him the questions my clients ask me. A few of his answers corrected things I thought I knew.
I started with mine. Can an appeal make your assessment go up? His answer: in theory yes, but it's unusual. The way it tends to happen is that you appeal, the county takes a closer look, and something turns up that wasn't in their records. If you built an addition the Assessor never caught, an appeal is when they'll find it, because you're the one handing them updated information about your property.
If the county's records on your place are accurate, this isn't much of a risk. If they're not, go in knowing that.
First, deal with the bill in front of you
Second installment bills for tax year 2025 went online August 18 and were mailed by September 1. They're due October 1. They're roughly two months late this year because of the county's property tax system overhaul.
Before you pay, check your exemptions. This is the one thing that affects the bill on your counter right now.
Exemptions come off the second installment, not the first. The Homeowner Exemption is the main one for owner-occupants, and it's supposed to renew automatically once established. (You may want to check every year to confirm it has been renewed.) A refinance, a deed change, a name change, or a transfer between spouses can knock it off, and you'll only find out by looking. There are also exemptions for seniors, the Senior Freeze, and veterans with disabilities, each with their own qualifications.
If you find you've been missing one you qualified for, you can get that money back. The county has a process for it, and there are millions in unclaimed refunds sitting there. Start at the Cook County property tax portal, where you can look up your PIN, see your exemptions, and check whether a refund is available on your property. Exemption details and applications are on the Cook County Assessor's site.
The trap runs in the other direction too, and this one caught me. I lived in the Humboldt Park two-flat before I bought my current place. When I moved out and kept it as an investment property, I had to go to the Assessor's website and file a form telling them to remove the homeowner exemption from it. They don't lift it automatically just because you bought somewhere else and claimed one there. If you end up holding a homeowner exemption on two properties, the county will catch it, and you'll be fined.
Nobody walks you through that at closing. If you've bought a second place and held onto the first, go check that you're not still claiming an exemption you're no longer entitled to.
While you're in there, compare this year's full tax year total to last year's full tax year total. Do not compare the second installment to the first. The first installment is a flat 55% of the prior year's total bill, calculated before anything about your actual property is considered. The second installment is where the real math lands. That structure makes almost every second installment look alarming, whether or not anything has changed.
What an appeal actually does
An appeal doesn't lower your taxes. It lowers your assessed value. Those aren't the same thing, especially in a reassessment year.
The paralegal I spoke with gave me an example. Say the county proposes a market value of $600,000 on a property last assessed at $430,000. That's a substantial increase, and a successful appeal doesn't undo it. What it does is blunt it. Instead of going from $430,000 to $600,000, maybe you land at $550,000. Your taxes still go up compared to last time. You just saved the difference between $600,000 and $550,000.
There's a second reason your bill can rise while your assessment falls. Your bill depends on your property's share of the total assessed value in your area, plus the levies set by your taxing bodies: schools, parks, the city. The Assessor doesn't control any of that. If everyone around you gets reduced more than you do, your share goes up regardless of what your own number did.
When not to bother
If you have a Senior Freeze or a veterans exemption, the advice I got from the firm is not to bother. Those freeze or reduce your assessment in a way an appeal isn't going to improve on, so you'd be spending effort with no upside. If your situation is unusual, like a partial exemption or a recent change in eligibility, ask before you assume this applies to you.
The mistake almost everyone makes
Most people who appeal file with the Cook County Assessor's Office and stop there. According to the paralegal I spoke with, that's the single biggest error homeowners make.
The Assessor is the office that set your value in the first place. The Board of Review is a separate, independent, elected body, and it exists specifically for taxpayers to challenge assessments and make sure they're being assessed uniformly with comparable properties. That's the venue you actually want. You can file there regardless of whether you filed with the Assessor first.
The timing problem
Cook County's 38 townships each get their own filing window, roughly 30 days, opening on a rolling schedule tied to when the Assessor publishes each township's assessment roll. The Board of Review then runs its own window for that township afterward. Your neighbor two miles west can be in a different month than you.
The problem usually isn't that people decide not to appeal. They mean to do it, and by the time they remember, their window has closed.
One more thing, because it comes up every September. The bill arriving is not the appeal window. Appealing today doesn't change the bill you're about to pay. It affects a future one.
If you live in Chicago, next year is your year
Cook County reassesses on a three-year rotation. The northern suburbs were reassessed in 2025. The south, southwest, and western suburbs are being reassessed in 2026, for taxes payable in 2027.
The City of Chicago is up next year.
The value the county proposes next year is the one your bills run on for the three years after that. A reduction generally holds until the following reassessment, so when you win matters as much as whether you win.
I have this in my own paperwork. My 2023 appeal came the year before a reassessment, so that reduction lasted one year before the Assessor came back with a new number. My 2025 appeal runs until 2027.
Which makes 2027 the one to be ready for. This is the winter to learn how the process works.
Three ways to do it
File it yourself. It's free at both the Assessor's office and the Board of Review, and it's all online. You don't need an attorney. This is worth repeating because I heard it directly from a property tax law firm: if you don't want to pay anyone, at minimum go to the Cook County Board of Review's website and read through their appeal process so you know what you're looking at when your township opens.
Pay a flat fee. Danny DeOliveira on my team uses DIY Property Tax Appeal and has had good results with it. The name undersells what it does. You aren't filing anything yourself. They pull the comparable properties, build the uniformity argument, and their in-house attorney files at the Assessor and the Board of Review. You fill out a questionnaire and sign an authorization. The difference from an attorney on contingency is that you pay a flat rate up front whether or not you win, rather than a share of a reduction you actually got.
Which is cheaper depends entirely on your outcome. On my 2023 appeal the contingency fee was $173, close to what a flat-fee service charges. If you win big, the flat fee is the better deal. If you win nothing, contingency costs you nothing.
Hire an attorney. This is what I do. The firm files on my properties every year and gets paid only if they win.
There's a small flat charge for expenses, then a contingency fee of a third of the first year's estimated savings. A third sounds like a lot until you remember that a reduction generally holds until your next reassessment. If that's three years out, you pay a third of one year's savings and keep the reduction for all three, which comes to about a ninth of the total. If your next reassessment is a year away, you pay a third for one year of benefit. On a large enough reduction, the fee is negotiable.
I'm not going to pretend I file these myself. The DIY version isn't hard, but the fee has never struck me as expensive. I'm just the kind of person who would often rather pay someone to handle a thing than handle it, and this is a thing I'd rather not handle. I don't hear from them during the year. It happens without me.
What it actually gets you
Here are two real results from my two-flat in Humboldt Park, both won at the Board of Review and filed by the property tax law firm I use.
In 2023, the Assessor had it at $27,000 in assessed value. The Board cut it to $24,455, a reduction of $2,545, which worked out to an estimated $523 in first-year tax savings. The legal fee was $173. In 2025, the Assessor came in at $35,000 and the Board brought it to $32,600, a $2,400 reduction and roughly $484 in savings. That fee was $160.
So: about $350 one year and $325 the other, after paying someone else to do the work. Some years nothing comes back at all.
That's smaller than the numbers you'll see promised elsewhere. Most sites writing about this are appeal firms with a stake in you filing. A few hundred a year, on something that costs nothing to attempt, is a good return. It just doesn't make a good headline.
One last thing, because everyone asks why we pay a year behind and nobody ever seems to know. The paralegal I spoke with explained it, and Cook County Treasurer Maria Pappas has written the same history: during the Great Depression, so many people couldn't pay that Illinois and Cook County delayed collection by a year. It was meant as relief. The system never caught back up. Almost a century later, we're all still paying last year's taxes this year.
Look up your PIN, confirm your exemptions, and check the Assessor's appeal calendar to find out when your township opens. If you're in the city, mark it down, because our assessments are next.
FAQ
Can appealing my property taxes make them go up?
It's uncommon but possible. The likeliest way is that the appeal prompts a closer look and the county updates their records. If, for example, you built an addition they never recorded, an appeal is when they'll find it. If your property matches what the county already has on file, this isn't much of a risk.
Should I appeal every year?
Generally yes. The exception the property tax firm I use gives is a Senior Freeze or a veterans exemption. In those cases an appeal isn't going to improve on what you already have.
Where should I file my appeal?
The Board of Review. Most people file with the Assessor and stop, which is the biggest mistake homeowners make. The Assessor is the office that set your value in the first place. The Board of Review is an independent elected body that exists for taxpayers to make sure they're uniformly assessed.
When is the Cook County property tax appeal deadline?
There isn't one date. Each of the county's 38 townships has its own roughly 30-day window, opening when the Assessor publishes that township's assessment roll, with a separate Board of Review window afterward.
Do I need a lawyer to appeal my Cook County property taxes?
No. Filing at the Assessor's office and the Board of Review is free and can be done yourself online. I use an attorney because I'd rather pay someone to handle it than handle it, not because the process requires one.
How much will I save if I win?
On my properties, often a few hundred dollars, sometimes nothing. And in a reassessment year, a win frequently means your taxes rise less than they were going to rather than dropping outright. Anyone quoting you a number before looking at your assessment is selling something.
My second installment bill is way higher than my first. Did my taxes double?
No. The first installment is a flat 55% of last year's total. The second installment is where the actual calculation happens, including exemptions. Compare full year to full year.
