The second installment of Cook County’s tax year 2025 property tax bills is due Thursday, October 1, 2026. The bills went out about two months later than usual because of problems with the county’s new property tax system. If you are buying in Chicago this fall, these bills are part of what your attorney reviews before closing.
Last reviewed September 30, 2026 · Chicago First Time Home Buyer editorial team
Cook County tax dates
| Bill | Due date | How it is set |
|---|---|---|
| Tax year 2025, first installment | Wednesday, April 1, 2026 | 55% of the prior year’s total bill |
| Tax year 2025, second installment | Thursday, October 1, 2026 | The balance, based on current assessments, rates and exemptions |
Why the bills were late
County officials said in June 2026 that the second installment would arrive about two months late because of ongoing problems with an overhaul of the property tax system. On August 18, 2026, the county confirmed that about 1.8 million bills would be mailed by September 1 with an October 1 due date. The year before, the second installment for tax year 2024 was not due until December 15.
What this means if you are buying
- Taxes are billed a year later. Tax year 2025 bills are paid in 2026. A home you buy this year will still have bills for earlier tax years coming due.
- Ask how taxes are split at closing. Your attorney and title company handle how taxes owed by the seller are credited or paid. Ask to see the figures before you close.
- Confirm the second installment was paid. If you close after October 1, ask your attorney to confirm the tax year 2025 second installment was paid on time. Unpaid taxes add interest that has to be settled at closing.
- Check the exemptions on the bill. The seller’s exemptions do not carry over to you. Plan to file for the Cook County Homeowner Exemption once you live there.
If the October 1 deadline is missed
Under Illinois law, property taxes not paid in full by the due date are charged interest of 0.75% per month. That rate applies to tax year 2023 and later bills; it was 1.5% per month before. Taxes that stay unpaid can be offered at the county’s Annual Tax Sale, which takes place roughly a year after the second installment due date. The Treasurer’s website has a payment plan calculator for owners who need to pay late taxes in smaller amounts.
Common questions
When is the Cook County property tax second installment due in 2026?
Thursday, October 1, 2026, for tax year 2025.
What happens if I pay the second installment late?
Interest of 0.75% per month is added to the unpaid amount. Taxes left unpaid long enough can be offered at the county’s Annual Tax Sale.
How is the first installment calculated?
It equals 55% of the prior year’s total tax bill. The second installment covers the rest, based on the current year’s assessment, tax rates and exemptions.
Where do I pay or look up a bill?
On the Cook County Treasurer’s website, which lists due dates and payment options.
Sources
- Cook County Treasurer’s Office, property tax due dates
- Cook County Government, second installment bills expected by September 1, due October 1, August 18, 2026
- WTTW News, second installment of 2025 bills will be two months late, June 9, 2026
- Cook County Treasurer’s Office, late payment interest (0.75% per month for tax year 2023 and later) and payment plan calculator
- JVM Lending, Cook County property taxes guide (first installment calculation)