Cook County Property Tax Appeal FAQs

A denial isn't the end. Cases can be escalated from the Assessor's Office to the Cook County Board of Review, then to the Illinois Property Tax Appeal Board (PTAB) at the state level, and in some high-value or complex cases to the Circuit Court of Cook County via a tax objection.

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

Three different bodies can decide a Cook County appeal, and they run on very different clocks. The short answer: the Assessor usually answers within the same calendar year, the Board of Review adds months on top, and the state board takes years.

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 31 December 2025, and the busiest single month was November, with 72,961 decisions issued.

So a typical Assessor appeal is a wait of months, not weeks. 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 neighbours 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 the deadline is worth diarising 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.

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 is 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.

A Cook County tax bill is not a percentage of what your home is worth. It is the end of a four-step calculation, and an appeal changes the first number in it.

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.

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.