Cook County, Illinois property tax works differently from most places: the payment dates move from year to year, and several offices each do one part of the job. The Assessor values property, the Clerk works out the tax rates, and the Treasurer sends the bills and collects. This guide shows the due dates the Treasurer has published for recent tax years, how a bill is calculated, and the exemptions that cut it. It does not state a tax rate for any area, because rates differ by taxing district.
Property tax is billed one year behind: tax year 2025 bills are paid in 2026. The Treasurer lists these due dates:
| Tax year | First installment due | Second installment due |
|---|---|---|
| 2025 | Wednesday, April 1, 2026 | Thursday, October 1, 2026 |
| 2024 | Tuesday, March 4, 2025 | Monday, December 15, 2025 |
| 2023 | Friday, March 1, 2024 | Thursday, August 1, 2024 |
The second-installment date has ranged from August to December in these three years, so do not assume a date from a previous year. The Treasurer's page showed no due dates for tax year 2026 when we read it on 9 November 2026, so watch the Treasurer's site and your mailed bill for them. Late taxes accrue interest of 0.75% per month for tax year 2023 and later bills (the rate was 1.5% per month for taxes due in 2023 and earlier), according to the Treasurer's news releases; the Treasurer's September 2026 release says balances unpaid after the October 1, 2026 deadline are charged 0.75% per month. Check your bill for the exact amount owed.
The Cook County Clerk explains the chain. The Assessor's office establishes property valuations. Taxing districts, which are the local governments that levy property tax, file their levy requests with the Clerk's Tax Extension Unit. The Unit determines the rate needed per $100 of taxable value to produce the requested revenue, based on the value of all taxable property within the district. Illinois law can restrict the revenue, either through statutory maximum rates for certain purposes or through "tax caps" that limit the total amount extended.
The Treasurer adds that exemptions reduce a home's Equalized Assessed Value (EAV), which is multiplied by the tax rate to determine the tax bill. Because every taxing district sets its own levy, the rate on your bill depends on where the property is, and this page does not give one. As a pure arithmetic illustration (an invented rate, not a real one): an exemption that removes $10,000 of EAV saves $600 if the combined rate is 6.000 per $100, because $10,000 x 6.000% = $600.
| Exemption | What it does | Who qualifies |
|---|---|---|
| Homeowner Exemption | Reduces EAV by $10,000 (since tax year 2017) | Primary residence that is a single-family home, townhouse, condominium, co-op or apartment building of up to six units; first-time applicants must have occupied the property on January 1 of the tax year |
| Senior Citizen Homestead Exemption | Reduces EAV by $8,000 | Owned and occupied the property on January 1 and aged 65 or older during the tax year |
| Senior Citizen Assessment Freeze ("Senior Freeze") | Freezes the property's EAV in the year the senior qualifies, so it does not increase while they continue to qualify | Over 65, total annual household income of $65,000 or less, owned and occupied the home on January 1 of the tax year |
The Treasurer says exemptions are reflected on the second installment tax bill. The Assessor's office automatically renews Homeowner Exemptions for properties that were not sold to new owners in the last year, and the Treasurer says the same about Senior Citizen exemptions. New owners need to apply to the Assessor. The Senior Freeze is different: the Treasurer says that once you have received it you must re-apply every year. This guide does not cover the other exemptions the county offers (for example for persons with disabilities or veterans).
The Cook County Assessor's and Board of Review's sites blocked our tools, so we do not describe assessment appeals or give assessed values. The Illinois statute that sets late-payment interest did not load for us either, so the interest rates above come from the Treasurer's own news releases. This page is a guide to dates and exemptions; use the Treasurer's property tax portal for your exact bill and payment history.
All figures on this page were read from these pages on 9 November 2026. Where a page below says it could not be read, that is stated in the text.