How to Appeal Your Property Taxes in Illinois (and Which County's Rules Actually Apply to You)

by Brian Wittman

You can appeal your assessment yourself. It's free at the first level, you don't need a lawyer, and if you win as an owner-occupant the reduction follows you for years, not just one bill.

Here's what nobody tells you before you file.

A Lake County homeowner appealed his 2021 assessment. His board of review had him at $160,165, and he went to the state board asking for $143,387. In February 2024 that board came back with $216,092. He didn't get a reduction, he got a thirty-five percent increase, and he had an attorney representing him the whole way.

How do you appeal property taxes in Illinois?

You file a complaint with your county's board of review, and you do it in the window your township or county opens, not whenever you notice the bill. If that doesn't get you where you need to be, you take it to the state or to court.

The process is close to uniform across Illinois. The calendar is not. That second part is what costs people the year, and it's the whole reason this page exists.

Three things worth knowing before you go any further.

You're appealing your assessed value, not your tax bill. The Illinois Department of Revenue says it plainly: "you are appealing the assessed value of your property, not the tax bill." Nobody here can lower your rate. Your school district asked for what it asked for.

By the time your bill shows up, you're usually too late. IDOR again: "Once you receive the tax bill, it is generally too late to make an appeal for that year's assessment." Your window runs off your assessment notice. Not your bill.

And yes, they can raise it. More on that below. You'll read the opposite somewhere.

What are the three levels of appeal?

Level one: your assessor

Not technically an appeal, and skipping it is a mistake.

Your assessor set the number. In most of Illinois that's your township assessor, not the county, which surprises people who've never thought about what a township does. A phone call that corrects a wrong square footage or a basement the record thinks is finished can fix the whole problem without a form.

Level two: your county board of review

This is the real first level, and for most homeowners it's the only one they need.

It's free. You can represent yourself. You file a complaint, you submit evidence, and in most counties you can ask for a hearing.

One hard rule: show up. If your appeal gets dismissed because you didn't appear at your board of review hearing, the state board loses the ability to hear you at all. The statute says so outright, that it "shall have no jurisdiction" over a complaint dismissed for failure to appear. You don't get to skip a step and try again upstairs.

Level three: PTAB, or circuit court, and you pick one

After the board of review, you have two roads.

The Illinois Property Tax Appeal Board is a state board, it's free to file, and you don't need a lawyer. Your appeal there is heard de novo, which PTAB explains in plain language: your case is considered "as if the board of review never heard or decided your assessment appeal." Nothing carries over. You start clean.

Circuit court is the other road, and it costs more before you file anything. You have to pay the tax in full first, within 60 days of the first penalty date on the final installment. Your payment is then automatically treated as paid under protest. Then you file, 75 days after that date in most counties, 165 in Cook.

You pick one for your valuation fight. File with PTAB and you're precluded from making a valuation objection in court. File in court first and you're precluded from PTAB. That's in the statute and in PTAB's own rules, both directions.

For most homeowners PTAB is the better road, and here's the concrete reason. In circuit court you have to prove your case by clear and convincing evidence, on every contested fact. At PTAB, a market value case only needs a preponderance. Same house, same argument, lower bar.

One thing that is not optional either way: you have to go through your board of review first. A court won't hear an objection if the administrative remedy existed and you didn't use it.

What are the grounds for a property tax appeal?

Three, and picking the right one decides what evidence you need.

1. Factual error

Your property record is wrong about your house. Wrong square footage, a room count that doesn't exist, a basement listed as finished when it's studs, a garage that isn't there.

This is the cheapest appeal to win because it isn't really an argument. You're correcting a record, and the evidence is a measurement or a photograph.

One thing worth knowing: this is a board of review ground. PTAB's own list of grounds doesn't include factual error. By the time you're at the state level, a record error has to be argued as value or as uniformity instead. So fix the record early.

2. Overvaluation

Your assessment says your house is worth more than it is. Assessed value is supposed to be one third of fair cash value outside Cook County, so an assessment of $133,000 claims a $400,000 house.

A recent arm's length purchase is the strongest evidence there is for this. If you bought the place last year for less than the assessor thinks it's worth, that's not an opinion, it's a transaction.

Otherwise you're looking at sales comparables, and PTAB puts a floor on how many. Its rules list acceptable proof of market value as an appraisal, a recent sale of your own property, documented construction cost, or "not fewer than three recent sales of suggested comparable properties." Three is the minimum, not the goal.

3. Uniformity

Your assessment is out of line with the houses around you, even if the market value is arguably defensible.

This is the one almost nobody explains to homeowners, and it's built into the Illinois Constitution. Article IX, Section 4 requires that "taxes upon real property shall be levied uniformly by valuation." The Property Tax Code says the same thing from the other direction: your property can't be assessed "at a higher percentage of fair cash value than other property in the assessment district."

So if every comparable house on your block is assessed at $110,000 and you're at $133,000, that's a real argument even if $133,000 is a fair number in isolation.

But it costs you more to prove. A market value appeal needs a preponderance of the evidence. A uniformity appeal needs clear and convincing evidence. That's PTAB's own rule, and it's the single most important sentence in this article for anyone planning a comps-based case.

PTAB is specific about what actually wins one. "Isolated examples of assessment inequities are not sufficient." Your comparables should usually sit in "the same neighborhood or subdivision." And proof "should consist of more than a simple showing of assessed values per square foot," because you also need physical, locational and jurisdictional similarity.

That's a real standard, and it's why pulling the right comparables matters more than pulling a lot of them. How to find comps for a property tax appeal is the part that does that work.

Can your assessment go up if you appeal?

Yes, it can. You'll read otherwise, and that's wrong.

I've seen it claimed that the risk of an increase during review is virtually nonexistent. It isn't nonexistent, because the law expressly provides for it. Your board of review may revise your assessment "upon application of any taxpayer or upon its own motion," and it can "increase, reduce or otherwise adjust" it.

What the law gives you is warning, not immunity. Your assessment "shall not be increased unless that person or his or her agent first has been notified in writing" and given a chance to be heard. The protection exists because the power does.

There's a real ceiling on it, and it's the same uniformity principle from above running in your favor. The board can't assess you at a higher percentage of fair cash value than other property in your district. So it can raise you, but not above the level everyone else is carrying.

At the state level, be more careful, because PTAB's rules give you no protection at all. Nothing in them promises your number won't go up, and PTAB does raise assessments.

Go back to the Lake County case from the top of this page. The homeowner appealed his 2021 assessment on overvaluation, and he brought three comparable sales from his own neighborhood to prove it.

Then the board of review brought in something he hadn't accounted for. His house had sold in October 2021, during the tax year he was appealing, for $649,900, listed and gone in a single day. The board put that sale in the record and asked PTAB to raise his assessment to match it.

PTAB agreed. Its decision opens with the words "An Increase... is warranted." It set his assessment at $216,092, which is that sale price taken at right about a third. That is $55,927 more than he started with.

The reasoning is old and settled. A contemporaneous arm's length sale is, in the Illinois Supreme Court's words, "practically conclusive" on what a property is worth. Three comparables can't beat your own sale price. Nothing can.

And he couldn't get out of it. His attorney filed to withdraw the appeal once it turned against him, but never served the board of review the way PTAB's rules require. PTAB emailed counsel about the defect and nothing was properly refiled, so the withdrawal never took effect and the increase stood.

Two things to take from that, and they're the most useful sentences on this page. If your house recently sold for more than your assessment implies, you don't have an overvaluation case, and filing one invites that sale into the record. And once you've filed, backing out is a procedure with its own service rules, not just a change of mind.

None of that means don't appeal, because most appeals look nothing like this one. It means bring real evidence, know what's already sitting in your own record, and don't file on a hunch.

How long do you have to file?

To PTAB: 30 days. Outside Cook, that clock starts on the date of the written notice of your board of review's decision, not the day you open the envelope. In Cook it's 30 days from the notice or 30 days from the board's final action on your township, whichever is later. Mailing counts, so the postmark is what governs.

To circuit court: 75 days after the first penalty date in most counties, 165 in Cook, and only after you've paid in full.

To your board of review: this is the part that isn't statewide, and it's the reason the next section exists.

Two traps worth naming. Your evidence goes in with your petition, and PTAB won't accept more later unless you request the extension at the same time you file. Ask for it and the 30-day extension is automatic. And if you're a corporation, an LLC, a land trust or a condo association, you must be represented by an Illinois attorney at PTAB. An individual homeowner can represent themselves. An entity can't. If you hold title in an LLC for liability reasons, that decision just cost you the right to self-represent.

Which county's rules actually apply to you?

The process above is close to the same everywhere in Illinois. The calendar is set county by county, and inside Cook, township by township.

That's fine if you know which county you're in. Out here, a surprising number of people don't.

Your mailing address doesn't settle it. Minooka sits in three counties, Will, Kendall and Grundy. Channahon straddles Will and Grundy. Lemont is mostly Cook with a Will edge. Tinley Park crosses the Cook and Will line. In every one of those towns, two neighbors can be on different filing calendars entirely.

What settles it is your parcel number. It's on your tax bill and in your county's property search, and it tells you your county, your township and your tax code. Everything else is a guess.

Cook runs its own shape on top of this. It reassesses on a triennial cycle, one third of the county each year, and each township opens for appeals when its notices mail and closes on its own date. So "the Cook deadline" isn't a thing. Your township's deadline is.

The rest of the state runs a four-year general assessment cycle and opens on a publication-driven schedule instead, which is why a Grundy County window and a Will County window rarely line up in the same month.

Once you know your county, the calendar and the filing mechanics are here:

How to appeal your property taxes in Will County
Appealing your Cook County property taxes, and if a reassessment notice just landed, how to read your Cook County reassessment notice first
How to appeal your property taxes in Grundy County
How to appeal your property taxes in Kankakee County

What you actually win

This is the part that makes the whole exercise worth an afternoon.

If you win at PTAB and you live in the house, the reduction sticks. The statute says a lowered assessment on a parcel "on which a residence occupied by the owner is situated" stays in effect "for the remainder of the general assessment period," unless you sell in an arm's length transaction or the decision gets reversed.

Outside Cook that's the rest of a four-year cycle. In Cook it's the rest of the triennial. So one successful appeal isn't one cheaper bill. It's several.

PTAB notes the Code is silent about carrying reductions forward for commercial and industrial property, so this is an owner-occupant benefit specifically. If you live there, it's yours.

One practical note while you wait: filing doesn't pause the bill. Taxes get extended and come due on schedule, and if you win you get an abatement or a refund with interest. PTAB's own advice is to pay on time.

The Bottom Line

You don't need a lawyer, you don't need to pay a percentage of your savings to anyone, and at the first two levels it doesn't cost you anything but time.

What you do need is the right ground and the right evidence. A record error is a correction. An overvaluation case wants a purchase price or real sales comps. A uniformity case wants assessment comparables from your own neighborhood, and it has to clear a higher bar than the other two.

And you need your own county's calendar, which is the piece most people get wrong, because the process is statewide and the deadline never is.

Start with your parcel number. Everything else follows from it.

Frequently Asked Questions

Is it worth appealing your property taxes?

If your assessment is wrong, yes, because the win compounds. As an owner-occupant, a reduction at PTAB carries for the rest of the assessment cycle rather than one year. The first two levels are free and you can do them yourself, so what you're really spending is an evening pulling comparables. If your assessment is defensible, though, skip it. An appeal opens your file, and at the state level there's no rule stopping your number from going up.

What's the best reason to protest property taxes?

Whichever one your evidence supports. A factual error in your record is the easiest to win and the cheapest to prove. Overvaluation is strongest if you bought recently for less than your assessment implies. Uniformity is the one to use when your number is out of step with your neighbors', but it carries the heaviest burden of proof of the three.

Can I appeal my property taxes myself without a lawyer?

Yes, at every level, as long as you hold title in your own name. PTAB says outright that no party needs to be represented by counsel. The exception matters though: corporations, LLCs, land trusts and similar entities must be represented by an Illinois attorney.

Is it too late to appeal property taxes in Illinois?

For the current year, probably, if your bill has already arrived. Your window runs off your assessment notice, not your bill, and once the bill is out that year is usually closed. Your next window opens when your township or county publishes its assessments again, so find that date now.

How do I lower my property taxes in Illinois?

Two levers, in this order. Make sure every exemption you qualify for is actually on your bill, because that's an application rather than an argument. Then, if your assessed value still looks too high, appeal it. What you can't touch is the rate. No board in this process has any authority over what your school district asked for.

What if my appeal gets denied?

You go up a level. A board of review denial can go to PTAB within 30 days of the written decision, and that hearing starts over from scratch with no weight given to what happened below. Or you can go to circuit court instead, but not both, and not without paying the tax first.

If you've got an assessment notice in front of you and you're not sure whether you have a case, send it to me and I'll tell you straight.

If you want to know what a specific house in the southwest suburbs is really going to cost you before you own it, assessment and all, set up a time and I'll pull the parcel and run the real number with you.

Brian Wittman is a licensed real estate broker (Real Broker LLC), mortgage loan originator (NMLS #2646598, NEXA Mortgage, LLC, Equal Housing Lender), and life insurance producer (Levinson & Associates). This article is for educational purposes only and is not financial, lending, tax, or legal advice, an offer, or a commitment to lend; all loans are subject to credit approval. Information is accurate as of the publication date; for current details and full disclosures, visit https://bluejeanbroker.com/disclosures.