The second-installment Cook County property tax bill for tax year 2025 was due Thursday, October 1, 2026; an unpaid balance now accrues interest of 0.75% a month. It is the bill that carries your 2025 assessment, the 2025 tax rates and your exemptions, less what you paid on the first installment in April. You pay it to the Cook County Treasurer, and the cheapest way costs nothing: online, from a bank account, at cookcountytreasurer.com.
The short version
| Due | Thursday, October 1, 2026 (Tax Year 2025 Second Installment), now past; the next bill is the Tax Year 2026 first installment, in 2027 |
| Who collects it | Cook County Treasurer, cookcountytreasurer.com, 118 N. Clark Street, Room 112, (312) 443-5100 |
| Free way to pay | Online from a checking or savings account (ACH) on the Treasurer's site |
| Card payments | Accepted online; a third-party processor charges 2.08%, not refundable |
| Late charge | 0.75% of the unpaid balance per month |
| What you will need | Your 14-digit Property Index Number (PIN), on the bill |
What the second installment is
Cook County bills each tax year in two parts. The first installment, due April 1, 2026 for tax year 2025, was an estimate: 55% of the prior year's total, with no exemptions applied. The second installment is the real calculation. It takes your 2025 assessed value, multiplies it by the 2025 state equalizer and your tax code's 2025 rate, subtracts your exemptions, and then subtracts what you already paid in April. That is why a second installment can be much larger or much smaller than the first. For what is on the bill line by line, see Cook County second installment 2025.
Two things are settled by the time this bill arrives: the 2025 assessment (it was appealable in 2025) and the 2025 rate. What you can still check is your exemptions, below.
Six ways to pay
1. Online from your bank account (free)
On cookcountytreasurer.com, choose the option to pay online for free, enter your PIN or address, confirm the photo shows your property, and enter your bank routing and account number. There is no fee from the Treasurer or from your bank. The payment posts in two to three business days; save the confirmation, and if the status has not changed to paid after five business days, call (312) 443-5100. Start from cookcountytreasurer.com itself: other websites that offer to forward your payment charge for it and are not official.
2. Online with a credit or debit card (2.08% fee)
The Treasurer's site takes American Express, Discover, Mastercard and Visa, credit or debit, through a third-party processor that charges 2.08%, about $104 on a $5,000 bill. The fee is not refunded, even if an appeal later produces a refund of the tax itself.
3. By mail (free)
Mail a check with the payment coupon from your bill to Cook County Treasurer, PO Box 805438, Chicago, IL 60680-4116. Write your PIN, the taxpayer's name, the property address and the tax year and installment on the check. For U.S. Mail, the postmark date is your payment date, so a check postmarked by the due date is on time. Private carriers count the date it arrives. Allow about two weeks to post.
4. At a Chase branch (free)
Any of the nearly 400 Chase branches in Illinois, including those outside Cook County, accepts Cook County property tax payments, whether or not you bank there. Bring the payment coupon from your bill (or a duplicate coupon printed from the Treasurer's site) and cash, a check or a money order; write the same details on a check. Partial payments are accepted, and you get a dated receipt.
5. At a community bank (free, account holders)
More than 100 community banks in Cook County accept property tax payments from their own customers. The list is on the Treasurer's site under ways to pay.
6. In person at the Treasurer's Office
118 N. Clark Street, Room 112, Chicago, weekdays. Older delinquent balances (open-item and forfeiture redemption bills) can be paid only here or by mail, not online or at a bank, and a redemption bill starts at the Cook County Clerk's office.
| Method | Fee | Time to post |
|---|---|---|
| Online, bank account | $0 | 2–3 business days |
| Online, card | 2.08% | 2–3 business days |
| $0 | about 2 weeks | |
| Chase branch | $0 | about 1 week |
| Community bank | $0 | depends on the bank |
| Treasurer's Office | $0 | same day |
If your mortgage company pays it
If your taxes are paid from an escrow account, your lender pays the Treasurer for you. If the lender pays late or on the wrong PIN, federal law (RESPA) and Illinois law make the lender liable for the late charge, and it cannot pass that charge on to you. A few business days after each due date, look up your PIN on the Treasurer's site and confirm the bill shows as paid. Do not also pay it yourself; a double payment becomes a refund that can take months.
If you pay late
An unpaid balance accrues a late charge of 0.75% per month, $7.50 a month on every $1,000. Partial payments are accepted and reduce the balance the charge applies to. State law does not allow a formal payment plan, but the Treasurer accepts partial payments at any time and offers a payment plan calculator for spreading them out (see paying monthly). Partial payments do not keep delinquent taxes out of the annual tax sale; paying the overdue balance in full does. A pending appeal does not postpone the bill: pay on time, and a successful appeal comes back as a refund or a lower bill.
Owners of ten or more properties
Paying ten or more PINs through the Treasurer's online payment service carries a $2.00 processing fee per PIN, per installment, under a county ordinance; the Treasurer bills it at least once a year. Large managers can apply to the Treasurer's Third Party Agent program for electronic tax data and bulk payment.
Check your exemptions on this bill
The second installment is where exemptions show up: the Homeowner Exemption ($10,000 of equalized value), the Senior Exemption ($8,000) and the Senior Freeze. If one you qualify for is missing, it is corrected with a Certificate of Error, not an appeal, and the overpayment is refunded. Pay the bill as issued in the meantime.
This bill is closed. Next year's is not.
Nothing you do now changes the 2025 bill. What you can change is the 2026 assessment behind next year's bill, and Assessor appeal windows are open in several townships into late November (Thornton's is the last, through November 23), and the Board of Review is taking appeals for West Chicago, Lyons, Northfield and Stickney through November 6, 2026. Every township's dates are on the deadlines page.
We are a Cook County property tax law firm in Palos Heights: attorney and CPA. Our fee is 25% of the first year's savings, nothing if there is no reduction. Enter your address to see where your home stands, or run the free property check.
Questions
When are Cook County property taxes due in 2026?
For tax year 2025, the first installment was due Wednesday, April 1, 2026, and the second installment was due Thursday, October 1, 2026 (Cook County Treasurer). The Treasurer announces the Tax Year 2026 dates in the new year.
Can I pay my Cook County property taxes online for free?
Yes. Paying from a checking or savings account on cookcountytreasurer.com costs nothing. Paying by card online costs 2.08%, charged by a third-party processor.
Does a payment mailed on the due date count as on time?
Yes, if it goes by U.S. Mail: the postmark date is the payment date. A private carrier counts the date the payment arrives.
Can I pay in monthly installments?
Not under a formal plan: state law does not allow one. The Treasurer accepts partial payments, so you can pay monthly or biweekly toward the bill; anything unpaid after the due date accrues 0.75% a month.
I have a pending appeal. Do I still have to pay?
Yes. An appeal does not postpone the bill. A reduction comes back as a refund or a lower later bill; a late payment accrues 0.75% a month regardless.
