How to Appeal Your Property Taxes in Cook County (From Someone Who Did It)

by Brian Wittman

A couple of years ago I opened my own reassessment notice and my stomach dropped. The county's estimate of what my house was worth had jumped, and I knew exactly what that meant for the tax bill coming behind it. So I did something most people never do. I appealed it myself. No attorney, no firm, no fee. I pulled the comparable properties the Assessor's office suggested, added a few I found on my own, lined them all up against what homes like mine had actually sold for, and filed. My reassessed value came back about 18 percent lower than the year before.

That is the part nobody tells you. You can do this yourself, it is free at the first level, and you do not have to be an expert to win.

How do I appeal my property taxes in Cook County?

You appeal by filing evidence that your home's assessed value is too high, first with the Cook County Assessor's Office during your township's open filing window, and if you need to, a second time with the Cook County Board of Review. Both are free, both are done online, and you get two separate chances every cycle. The most common evidence is a set of comparable properties, meaning homes similar to yours that are assessed for less, backed up by recent sale prices. You do not need a lawyer to file, though you can hire one if you would rather not do it yourself. The whole thing starts with one number on your reassessment notice: your estimated fair market value.

Why would I appeal in the first place?

The simplest reason is that your assessment sets your tax base, and if that number is too high, you overpay every year until it changes. In Cook County, your home's assessed value is 10 percent of the fair market value the Assessor assigns it. So if the county says your house is worth $400,000, your assessed value is $40,000, and that $40,000 is what your tax rate gets applied to. Knock the market value down to $340,000 and the assessed value drops to $34,000. Same house, smaller base, smaller bill. (Those numbers are just to show the math.)

You have a case worth filing when the county's estimate is higher than what your home would actually sell for, when similar homes near you are assessed for less, when the county has a detail wrong (wrong square footage, wrong lot size, a basement counted as finished that is not), or when your property has condition problems that lower its value. Cook County reassesses every three years, so the value set this year rides your tax bill for the next three. That is what makes a reassessment year the moment to look closely. One appeal can pay off for the whole cycle, and managing that number is part of managing what your home costs you over the years you own it.

Here is the honest part. Most homeowners never appeal. A lot of them do not know they can, and the ones who do often assume it takes a professional. Nobody in the transaction is paid to tell you that you might be overpaying, or to walk you through fixing it yourself for free. That is exactly why it is worth understanding.

How do I find out when I can appeal?

Cook County does not open appeals for the whole county at once, and there is no single countywide deadline. Each township opens on its own rolling schedule, and once your window opens you have roughly 30 days to file with the Assessor. When your township is up for reassessment, the county mails you a Reassessment Notice, and the filing deadline is printed right on it.

There are two easy ways to find your window: check the deadline on your notice, or look up your township on the Cook County Assessor's assessment calendar. Because the windows roll through the year, some townships are open right now, some have already closed for this round, and some have not opened yet. If yours has closed at the Assessor level, do not assume you missed your shot. You still have the second one.

Where do I actually file? (You get two chances)

Cook County gives you two separate appeals each cycle, and this is the part worth slowing down for.

The first is with the Cook County Assessor's Office, filed online through their portal during your township's window. It is free, and the Assessor reviews your evidence and issues a decision, usually within a few weeks. This is the fastest path to a reduction.

The second is with the Cook County Board of Review, an independent body that opens its own filing period after the Assessor's decisions for your area are finished. Here is what most people miss: the Board of Review is a completely separate shot. You can file there even if you never appealed to the Assessor, and even if the Assessor turned you down. For a lot of homeowners, this second round is where a reduction actually lands. So if the first answer is no, or you missed the first window entirely, the Board of Review is your next move, not the end of the road.

And the numbers make the case better than I can. According to the Cook County Board of Review's own annual report, in Tax Year 2024 about half of all appellants (50%) won a property value reduction, and homeowners who filed on their own won more often, about 55% of the time, than those who hired an attorney, at about 48%. You do not need to pay anyone to have a real shot at this. Doing it yourself works.

What are the steps to file an appeal?

Here is the process, start to finish:

Find your window. Check your Reassessment Notice or the Assessor's calendar for your township's deadline.
Look up your property. On the Assessor's site, pull your property record and confirm the details are right: square footage, lot size, number of bathrooms, basement status. A factual error is one of the easiest wins.
Build your comparables. Find homes similar to yours in size, style, and area that are assessed for less than yours. This is the heart of the appeal.
Back them with sales. Line your comps up against what similar homes actually sold for recently. Assessed value is supposed to track market value, so real sale prices are strong evidence.
File online during your window and upload your evidence.
Wait for the decision, then decide whether to take the second bite at the Board of Review.

One thing I learned doing my own appeal: the Assessor's office will often suggest comparable properties for you. I used the ones they recommended and then added a few I found myself. Leaning on their own suggested comps makes it easier and faster for them to compare and say yes, and adding your own strengthens the case. You are not stuck with only what they hand you, and you are not starting from a blank page either.

This is general information on how the process works, not legal or tax advice. For the specifics of your property, confirm with the Cook County Assessor's Office or a qualified professional.

How do I check the status of my appeal?

After you file, you can track your appeal online. The Cook County Assessor's site lets you look up your appeal by your property's PIN or address, and once decisions are issued, your updated assessed value shows up there too. If you also filed with the Board of Review, that is tracked separately on the Board's own site. The short version: keep your PIN handy, and check the same official site where you filed.

The Bottom Line

Your property taxes are one of the largest ongoing costs of owning your home, and in Cook County the number they are built on is one you are allowed to challenge, for free, twice a cycle, without hiring anyone. If your assessment looks high, the worst case is you spend an hour building comps and the answer is no. The best case pays off for the entire three-year cycle. I did it on my own house and it worked.

If you would rather not do it yourself, that is fine too. There are attorneys and firms who handle these, and I am happy to point you to someone I trust. Either way, the mistake is doing nothing and quietly overpaying for years. If you want a second set of eyes on whether your assessment is even worth appealing, reach out. That is the kind of thing I am glad to talk through.

Frequently Asked Questions

How do I file a tax appeal in Cook County?

File online through the Cook County Assessor's portal during your township's open filing window, then, if you need to, a second time with the Cook County Board of Review. You submit comparable properties and recent sale prices as evidence that your assessed value is too high. There is no fee to file at the Assessor level.

What is the deadline to appeal my Cook County property taxes?

There is no single countywide deadline. Each township gets its own filing window, usually about 30 days, and the date is printed on your Reassessment Notice and posted on the Cook County Assessor's calendar. Once your window closes at the Assessor, you can still file with the Board of Review during its separate period.

Do I need an attorney to appeal my property taxes?

No. Many homeowners file their own appeals using comparable properties and sale prices, and it is free to file with the Assessor. In fact, per the Cook County Board of Review's 2024 annual report, homeowners who filed on their own won a reduction more often, about 55% of the time, than those who used an attorney, at about 48%. An attorney or appeal firm is an option if you would rather hand it off, but it is not required to file or to win.

What evidence do I need to appeal?

The strongest evidence is a set of comparable homes, similar to yours in size, style, and area, that are assessed for less, supported by recent sale prices. Correcting a factual error in your property record, like wrong square footage, lot size, or features, can also lower your assessment.

How is my Cook County assessed value calculated?

For residential property, your assessed value is 10 percent of the fair market value the Assessor assigns your home. Your tax rate is applied to that assessed value, so lowering the fair market value lowers the base your taxes are built on.

Can I still appeal if I missed my township's window?

Often yes. The Cook County Board of Review opens a separate appeal period after the Assessor's deadlines, and you can file there even if you missed or lost the first round. Check the Board of Review's site for your township's dates.

How often can I appeal?

You can appeal every year, and Cook County reassesses each property once every three years. In a reassessment year especially, it is worth a look, because the value set that year rides your tax bill for the full three-year cycle.

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 bluejeanbroker.com/disclosures.