Cook County Property Tax Appeal FAQs

Want to know if your assessment is too high? Check your property free →

The full guide: How do I appeal my Cook County property taxes? →

Want to know if your assessment is too high? Check your property free →

The full guide: Cook County Property Tax Appeal Attorney →

Want to know if your assessment is too high? Check your property free →

Want to know if your assessment is too high? Check your property free →

The full guide: Cook County Property Tax Appeal Fees: 25% of First-Year Savings →

A denial isn't the end. The Board of Review is independent of the Assessor, and you can file there whether or not the Assessor reduced your assessment. After the Board decides, you can go to the state Property Tax Appeal Board (PTAB) or, in some cases, file a tax objection in the Circuit Court.

For the full picture, see our guide to the Illinois Property Tax Appeal Board.

Want to know if your assessment is too high? Check your property free →

The full guide: Cook County Board of Review Appeals: The 2026 Guide (Deadlines, Odds, How to File) →

Want to know if your assessment is too high? Check your property free →

The full guide: The Cook County Assessor Appeal Process Explained →

Three different bodies can decide a Cook County appeal, and they run on very different clocks. The Assessor decides after your township's window closes, usually within a few weeks to a few months. The Board of Review decides later the same assessment year, before second-installment bills are issued. PTAB cases often take two years or more.

What the county's own record shows

For the 2025 tax year the Assessor issued 244,942 decisions. The first arrived in June 2025. By the end of September roughly four in ten were out; by the end of October about six in ten; by the end of November nine in ten. All but a hundred were decided by December 31, 2025, and the busiest single month was November, with 72,961 decisions issued.

Two things about that wait surprise people. It is counted from when your township's filing window closes, not from the day you file — so filing early does not move you up the queue, though it does mean you cannot miss the date. And the decisions come out township by township rather than all at once, which is why two neighbors who filed the same week can hear back months apart.

The Board of Review

If the Assessor's answer is not enough, the Board of Review takes the case fresh — it is not an appeal against the Assessor's reasoning, it is a second look at the evidence. The Board opens township by township after the Assessor certifies that township's roll, so when your window falls depends on where the property sits. Our deadlines page tracks each township's dates as the county publishes them.

The Illinois Property Tax Appeal Board

PTAB reviews Board of Review decisions at the state level, and it is the slow route — a backlog measured in years rather than months. The clock to file, though, is short: 30 days from the later of the Board's written decision or the date the Board sends its final action on your township to the Assessor, not from the day the letter reaches you. Missing it is jurisdictional, so put the deadline on your calendar the moment the decision arrives.

Does waiting cost you anything?

No. A reduction applies to that tax year whenever the decision lands. If the bill has not been issued yet, it is calculated on the lower figure; if you have already paid, the correction comes back to you. The practical consequence of the timeline is not risk, it is patience — and that the moment to act is while your township's window is open, because once it closes the only routes left are the Board, the state board, or a Certificate of Error where the county's record is factually wrong.

Look up your property to see which window applies to it.

The full guide: What happens after I file an appeal? →

Want to know if your assessment is too high? Check your property free →

The full guide: Cook County Residential Property Tax Appeal →

Assessed Value vs Market Value: What Cook County Homeowners Need to Know

Want to know if your assessment is too high? Check your property free →

The full guide: Assessed Value vs Market Value: What Cook County Homeowners Need to Know →

Want to know if your assessment is too high? Check your property free →

The full guide: Why did my property tax bill increase so much? →

Want to know if your assessment is too high? Check your property free →

Want to know if your assessment is too high? Check your property free →

A property tax assessment appeal asks the county to lower the value it put on your property, and so your tax. In Cook County you usually appeal to the Assessor, then the Board of Review, each in your township's filing window, then to the state Property Tax Appeal Board (PTAB) or the Circuit Court. Filing at the Assessor, the Board of Review and PTAB is free.

What an appeal changes, and what it does not

An appeal is about your property's assessed value, the figure your tax bill is calculated from. You do not appeal the bill itself, and the tax rate is not part of it. Homes and apartment buildings are assessed at 10% of market value, and most commercial property at 25%. The tax rates, and the amounts your school district, village and the county ask for, are set elsewhere, so an appeal cannot change them. A lower assessment usually lowers your bill, because your share of the total falls. If your assessment is reduced, the lower tax shows on your second-installment bill the following year.

The grounds: similar properties, market value, record errors

You have a case if any of these is true: similar properties nearby are assessed lower; the Assessor's market value is higher than the property would sell for; or the county's record of it is wrong, for example its size.

• Similar properties assessed lower. Compare homes in the same neighborhood and the same class code, as close to yours in age and style as you can find. Divide each home's building assessment by its building square footage; if yours is higher per square foot, that gap is your case.
• Market value. If you bought the property in the past three years, in an arm's-length sale, for less than the Assessor's market value, your closing documents are your evidence. Recent sales of similar homes, or an appraisal, can show the same.
• Record errors. If the county lists the wrong size, age or features, correcting the record can lower the assessment on its own.

Where an appeal is filed

You can challenge a Cook County assessment at up to three levels, in this order: the Cook County Assessor, the Board of Review, and then the Illinois Property Tax Appeal Board (PTAB) or the Circuit Court. The Assessor is optional, but filing there gives you two chances at a reduction instead of one.

• The Assessor decides after your township's window closes, usually within a few weeks to a few months.
• The Board of Review decides later the same assessment year, before second-installment bills are issued.
• After the Board of Review decides, you can go to PTAB or to the Circuit Court, not both. PTAB cases often take two years or more.

Each township's filing dates are on our deadlines page.

How often you can appeal

You can appeal every year, not only in your reassessment year. For a home, a reduction usually stays in place for the rest of your township's three-year reassessment cycle. The county can change it in a later year, so we review your assessment each year.

What it costs

Filing at the Assessor, the Board of Review and PTAB is free. If you choose the Circuit Court, you pay the court's filing fee; we tell you the amount before we file. If we file for you, our fee is 25% of first-year savings, only if your assessment is reduced.

Homes and commercial property

Homes are usually appealed on similar homes nearby or a recent purchase. A commercial assessment is an income calculation. The Assessor values most commercial buildings from the rent they earn and what they cost to run. So the case is built from the building's own records. If an LLC, corporation or other company owns the property, the Board of Review and PTAB require a licensed attorney to represent it.

How to start

The full guide: How do I appeal my Cook County property taxes? →

Want to know if your assessment is too high? Check your property free →

Look up your balance on the Cook County Treasurer's website using your 14-digit Property Index Number (PIN) or your property address. The record shows the amount due for the current installment, any unpaid prior years, payment history, and the due date. You can view or download the bill itself; no account is needed.

What you will see

• Current installment: the amount due and the due date. For the 2025 tax year the first installment was due April 1, 2026 and the second installment was due October 1, 2026 (what is on the October 1 bill).
• Prior years: any unpaid balance, with interest. Cook County charges 0.75% per month (9% a year) on late payments for tax year 2023 onward, per month or part of a month, so one day late costs a full month.
• Payment status: whether an escrow servicer has paid on your behalf. The record stays visible to you even when the paper bill goes to your lender.

If the amount looks wrong

Check that your exemptions appear on the bill. A missing Homeowner ($10,000 off equalized value) or Senior ($8,000) exemption is corrected through a Certificate of Error, not an appeal. If the exemptions are right and the bill still looks high, the assessed value behind it is the only part you can challenge — see How do I appeal my Cook County property taxes? and your township's deadline.

A faster way to see the whole picture

Enter your address or PIN in our free property check: it shows your current bill, your 20-year bill history with the PDFs, your assessment history, and whether the assessment is above what comparable homes are paying.

The full guide: How do I look up my Cook County property tax bill online? →

Your Cook County property tax is your assessed value (10% of market value for a home), times the state equalizer (3.0300 for the 2025 tax year), minus your exemptions, times your local tax rate. For a $300,000 home with the $10,000 Homeowner Exemption and a 7% rate, that is about $5,660 a year. An appeal lowers the assessed value.

The four steps

• Market value. The Assessor estimates what the property would sell for.
• Assessed value. A home (Class 2) is assessed at 10% of that market value. A $300,000 house has an assessed value near $30,000.
• Equalized assessed value. The state multiplies the assessed value by the equalization factor — 3.0300 for the 2025 tax year — to bring counties onto a common footing. Exemptions are then subtracted from this number.
• The bill. Your local tax rate, set by the schools, municipality, county and other districts that serve your address, is applied to what is left.

Worked through

$300,000 market value → $30,000 assessed → about $90,900 equalized. Take off the Homeowner Exemption's $10,000 and roughly $80,900 is taxed. At a 7% local rate that is about $5,660 a year; at 13%, about $10,500. The rate is why two identical homes in different townships pay very different bills — see the 2025 rates by township.

Which number an appeal changes

An appeal argues the assessed value, step two. Lower it and every step after it falls with it. It does not change the rate, which is set by the taxing districts, or the equalizer, which is set by the state. Run your own figures in the property tax calculator, or have a property tax attorney look at the assessment itself.

The full guide: Cook County Tax Appraisal & Property Tax Calculator →

Your payment history is on the Cook County Treasurer's website under your PIN or address: the amount billed and paid for each year, the payment dates, and a copy of each paid bill you can download.

Why people need it

• Illinois income tax: the Property Tax Credit on Schedule ICR is 5% of the property tax you paid during the calendar year on your principal residence (not allowed above $250,000 adjusted gross income, or $500,000 filing jointly), so you need the amount paid by calendar year, not by tax year.
• Closing or refinancing: lenders and attorneys ask for the last two paid bills.
• Escrow disputes: the Treasurer's record is the one your servicer's statement is reconciled against.

Tax year vs calendar year

Cook County bills a year in arrears. The 2025 tax year was billed in two installments due April 1, 2026 and October 1, 2026, so "taxes paid in 2026" means the 2025 tax year plus any late 2024 payments. See the 2025 tax year schedule.

The 20-year view

Our free property check lists every bill for the last 20 years with the PDF for each, next to the assessment that produced it, so you can see which years the bill rose because the rate rose and which because your assessment did.

The full guide: How do I look up my Cook County property tax bill online? →

The Cook County Property Tax Portal is the county's official site, run by the Treasurer; Cook County Tax Appeals is a law firm and is not part of it. Here is how to use the portal, and how to check whether your assessment is fair.

You can view your Cook County property tax bill online at the Cook County Treasurer's website using either your 14-digit Property Index Number (PIN) or your property address. Bills are posted online before they are mailed, so you can see what you owe — and confirm your exemptions — two weeks or more before the paper bill arrives. Viewing and downloading your bill is free.

Second Installment 2025 bills: the key dates

The bill stays online after the due date, with its payment status.

• Posted online: August 18, 2026
• Mailed: on or before September 1, 2026
• Due: October 1, 2026; an unpaid balance now accrues interest of 0.75% a month
• Bills issued: approximately 1.8 million

If the bill still shows a balance, interest is accruing every month until it is paid; if your taxes are escrowed, ask your lender to confirm it paid. Look at the exemptions on the bill too, and at whether the assessment behind it is worth challenging (see below). If the bill does not come up at all, see where your second-installment bill is.

How to look up your bill by PIN

1. Go to the Cook County Treasurer's website and choose the option to view or pay your bill.
2. Enter your 14-digit Property Index Number.
3. Select your parcel from the results.
4. View the current amount due, both installments, and payment status. A PDF of the bill can be downloaded and printed.

Step-by-step screenshots are in our guide to downloading your Cook County tax bill.

How to look up your bill by address

If you do not know your PIN, you can search by property address instead. Enter the street number, street name, and city or ZIP. Address searches sometimes return several parcels — condominium buildings, properties with an attached garage parcel, and split lots are common cases — so confirm the unit number and the parcel description before assuming the first result is yours.

What a PIN is, and how to find yours

A Property Index Number is the county's unique 14-digit identifier for a parcel of land, usually written in the form xx-xx-xxx-xxx-xxxx. Every one of Cook County's parcels has one, and nearly every county record — assessment, bill, exemption, appeal — is filed against it rather than against your name or address.

Your PIN appears:

• At the top of your property tax bill
• On your assessment notice from the Assessor's Office
• On your deed and on your title insurance policy
• On the closing statement from when you bought the property
• Through an address search on any of the county's property lookup sites

If you own more than one parcel — a home and a separately assessed garage or parking space, for example — each has its own PIN and its own bill.

Which official county site does what

Cook County splits property tax information across several offices, which is the single most common source of confusion for homeowners:

• Cook County Treasurer — what you owe, both installments, payment status, payment history, refunds, and the downloadable PDF bill.
• Cook County Assessor — how your property is valued: assessed value, characteristics on file, exemptions, and assessment notices.
• Cook County Property Tax Portal — a combined view that pulls from the Treasurer, Assessor, Clerk, and Board of Review, including appeal history.
• Cook County Clerk — tax rates by tax code, and the equalization factor applied to assessed values.

If you want the amount due, start at the Treasurer. If you want to understand why the amount is what it is, start at the Assessor. Our guide to Cook County property tax records online covers what each office publishes.

Paying online: free by bank transfer, 2.08% by card

Payment directly from a checking or savings account on the Treasurer's site is free and available around the clock. Paying by credit card carries a convenience fee of 2.08% — on a $6,000 bill that is roughly $125 for the convenience.

Other options include approximately 400 Chase Bank locations in Illinois, more than 100 participating community banks (which generally require the physical bill), payment by mail, and in person at the Treasurer's Office at 118 N. Clark Street, Room 112, in Chicago.

Partial payments are accepted and reduce the interest that accrues on an overdue balance. More detail is in our breakdown of payment options and deadlines.

What to do if your bill is missing or will not come up

A bill that does not appear online usually has one of a handful of explanations:

• The installment has not been posted yet. Second-installment bills in particular are released on a schedule that moves from year to year.
• The PIN was mistyped. All 14 digits are required; a single transposed digit returns nothing or returns someone else's parcel.
• The property recently changed hands or was divided. New PINs take time to appear, and a divided parcel may be billed under numbers that did not exist last year.
• Your mortgage servicer receives the bill. If taxes are escrowed, the paper bill may go to the servicer while the online record stays fully visible to you.

Escrow is worth a specific warning: a servicer pays whatever the county bills, without reviewing whether the assessment behind it is correct. An over-assessment inside an escrow account is invisible until your monthly payment jumps. See what to do about a missing tax bill.

Do I need an account or a login?

No. Viewing, downloading, and paying your Cook County property tax bill does not require registering for an account — the PIN or the address is enough. You may optionally sign up for eBilling to receive future bills by email; our eBilling guide explains how and what it does not change. If a site is asking you to create an account or to pay a fee simply to view a bill, confirm you are on an official county domain.

Your bill went up. Now what?

Looking up the bill is the easy part. The harder question is whether the number is right.

Your bill is the product of three things: the assessed value the Assessor placed on your property, the state equalization factor, and the local tax rate set by the taxing bodies where you live. You cannot negotiate the rate, and the equalizer is set at the state level. The assessed value is the only one of the three you can challenge — and it is the one most likely to be wrong, because it is generated by a mass-appraisal model rather than by anyone visiting your property.

Common reasons an assessment is too high:

• Square footage, room count, or condition recorded incorrectly
• Your assessment out of line with comparable homes on your block — the uniformity argument the county's own process is built around
• A finished basement or an improvement carried on the record that no longer exists, or never did
• A reassessment year that moved your township's values as a group without regard to your particular property
• Exemptions you qualify for that were never applied

Appeals are filed township by township, and each township's window is open for a limited period each year at the Assessor and again at the Board of Review. Check your township's current appeal deadline — if your window is open, the filing itself takes far less time than most people expect, and the process runs largely on paper.

Two things worth knowing before you decide it is not worth the trouble: a successful appeal reduces the assessed value that drives every future bill, not just this one, and a reduction can produce a refund where taxes have already been paid. Our fees are contingency-only — nothing upfront.

To see what a reduction would be worth on your own parcel, run the numbers in our Cook County tax assessment and property tax calculator, or read why Cook County tax bills rise for the mechanics behind the increase.

The Senior Freeze — formally the Low-Income Senior Citizens Assessment Freeze Homestead Exemption — locks the equalized assessed value of a qualifying home at its base-year level, so later reassessments cannot raise the taxable value. In a reassessment year it is the most valuable exemption a Cook County senior can hold.

Who qualifies

• Age: 65 or older — born in 1960 or earlier for the 2025 tax year.
• Income: total household income of $65,000 or less for the 2025 tax year (that is 2024 income). The limit rises to $75,000 for the 2026 tax year, $77,000 for 2027 and $79,000 from 2028 on. Household means everyone living in the home, and income includes Social Security, pensions, wages, interest and dividends.
• Residence: you owned and lived in the home as your principal residence on January 1 of the tax year and of the year before.

What it freezes, and what it does not

It freezes the equalized assessed value — the number the rate is applied to. Your bill can still rise if the tax rate rises, because the Freeze does not freeze levies. It stops the taxable value climbing; it does not push it below the base year.

The part people lose it on

It must be applied for every year. Unlike the Senior Exemption, it does not renew itself, and a missed year is a year at the unfrozen value. If you qualified and did not apply, a Certificate of Error can reach tax years 2021 through 2025.

The full guide, with the 2026 qualifying dates: Cook County Senior Freeze Exemption.

Apply to the Cook County Assessor. The Senior Exemption is for homeowners 65 or older who live in the home: apply once, with proof of age and ownership, and it renews automatically. The Senior Freeze also has an income limit ($65,000 for the 2025 tax year, $75,000 for 2026), and you apply for it every year.

The Senior Exemption

Apply once. You will be asked for proof of age and proof that you own and occupy the home — a driver's license or birth certificate, and a deed, tax bill or closing statement. Once granted in Cook County it renews automatically, so there is nothing to do in later years unless you move.

The Senior Freeze

Apply every year. As well as age and occupancy, it asks for total household income for the prior calendar year — $65,000 or less for the 2025 tax year, rising to $75,000 for 2026 — so it needs your income documents each time. A year not applied for is a year at the unfrozen value.

What to do about years already missed

An exemption you qualified for but did not receive is exactly what a Certificate of Error is for: tax years 2021 through 2025, paid back as a refund check from the Treasurer rather than credited forward.

Exemptions are not an appeal

Applying for an exemption lowers the taxable value. It does not challenge the assessment, and it does not use up your right to appeal — see the Senior Freeze guide for the qualifying dates, and check your parcel if you also think the assessment is too high. If you have the Senior Freeze, an appeal may lower your bill by less than it lowers your assessment. We check this before we file, and our fee is 25% of the first-year savings that reach your bill.

The full guide: Cook County Senior Exemption: $8,000 Off, Plus the Freeze →

Five things actually move an Illinois property tax bill, and they are not equally useful. In rough order of what they are worth to a typical Cook County owner:

1. Claim every exemption you are entitled to

An exemption reduces the taxable value of your home directly, and it is the cheapest saving available because it is not an argument — you either qualify or you do not. The Homeowner, Senior Citizen Homestead, Senior Freeze, Persons with Disabilities, Veterans and Long-Time Occupant exemptions each have their own test. Check which ones apply.

2. Appeal the assessment

An appeal argues that the county's opinion of your property's value is too high compared with similar properties. It is a separate lever from exemptions and the two do not compete: an exemption lowers the taxable value, an appeal lowers the assessment the exemption is applied to, and you can do both in the same year. Appeals are only accepted while your township's window is open — the deadlines page shows when that is.

3. Correct what the county has on record

The county's description of your property drives its value. Wrong square footage, a garage or bathroom that does not exist, the wrong class, a building that was demolished — each inflates the assessment until someone corrects it. Where the error is factual rather than a matter of opinion, a Certificate of Error can reach back beyond the current year.

4. Know where you are in the three-year cycle

Cook County reassesses one third of the county each year. A reassessment year is when your value moves most, and it is the year an appeal has the most to work with — but you can appeal in any of the three.

5. Read the comparable assessments yourself

Every assessment is an opinion about how your property compares with others. If similar homes nearby carry lower assessments, that gap is the case. This is the part most people cannot do from their own records, and it is the part an appeal turns on.

Start with your property and the deadlines that apply to it.

The full guide: Seven ways to lower your Cook County property taxes →