A Chicago property tax bill arrives twice a year from the Cook County Treasurer. The first installment is mailed by January 31 and is due March 1; it’s set at 55% of your prior year’s total tax. The second installment covers the balance once the Assessor finalizes values and taxing districts set their rates, and while state law targets a June 30 mailing with an August 1 delinquency date, it often runs months later. For Tax Year 2024, for example, the second installment wasn’t due until December 15, 2025.1Cook County Treasurer’s Office. Due Dates
Due Dates and Late Penalties
Cook County uses an accelerated two-installment cycle under the Illinois Property Tax Code. The first-installment estimated bill is mailed by January 31 and due March 1.2Illinois General Assembly. Illinois Code 35 ILCS 200/21-25 – Due Dates; Accelerated Billing in Counties of 3,000,000 or More Because that installment is fixed at 55% of the previous year’s total, you can estimate it before the bill lands.3Illinois General Assembly. Illinois Code 35 ILCS 200/21-30 – Accelerated Billing
The second installment reflects reassessments, the state equalization factor, and the year’s tax rates. Statute sets a June 30 mailing and August 1 delinquency, but delayed multipliers and assessments routinely push the actual due date months out. When the mailing is late, the printed due date moves with it, and no penalty accrues until after that date.
Late payments on either installment carry interest of 0.75% per month, or 9% annualized, on the unpaid balance. The rate used to be 1.5% per month; the legislature cut it in half starting with the 2023 tax year.2Illinois General Assembly. Illinois Code 35 ILCS 200/21-25 – Due Dates; Accelerated Billing in Counties of 3,000,000 or More
Finding Your Bill Online
Every parcel has a 14-digit Property Index Number, or PIN. The digits identify the township, section, block, and lot.4Cook County Assessor’s Office. Where Do I Find My PIN You’ll find yours on a prior tax bill, your deed, your closing paperwork, or any notice from the Assessor.
If none of those are in reach, look up the PIN by street address on the Cook County Assessor’s website. With the PIN in hand, go to the Cook County Treasurer’s website to view or download the current bill. The Treasurer’s portal also flags exemptions missing from prior years, which can trigger a refund through a certificate of error. When both installments for a tax year are posted at once, check the tax year on the bill so you don’t confuse them.
Reading the Numbers on Your Bill
The bill starts with the property’s Equalized Assessed Value, or EAV. Residential property in Cook County is assessed at 10% of estimated market value. The Illinois Department of Revenue then applies an equalization factor (the multiplier) that brings Cook County assessments into line with the rest of the state. For Tax Year 2024, the multiplier was 3.0355, so the Assessor’s figure gets multiplied by about three before rates apply.5Illinois Department of Revenue. 2024 Cook County Final Multiplier Announced The multiplier changes yearly and isn’t set until after the Assessor finishes the cycle, which is part of why second installments run late.
Exemptions come off next, producing a net taxable value. Each taxing district covering your property — schools, the Metropolitan Water Reclamation District, the Park District, city services, and others — applies its own levy rate. Those rates combine into the composite tax rate printed on the bill, and the breakdown lets you see where each dollar goes.
One boundary worth flagging: reassessments happen on a three-year rotation. Chicago proper is on its own group, so the 2026 general reassessment covers the south and west suburbs, not the city itself.6Cook County Assessor’s Office. Assessment and Appeal Calendar Individual Chicago properties can still be reassessed after new construction, a lot split, or a building permit.
Exemptions That Lower the Bill
Cook County exemptions reduce your EAV before rates are applied, and missing one can cost hundreds of dollars a year. The Assessor won’t always catch the oversight. The deadline to file for the 2026 tax year is May 15, 2026.7Cook County Assessor’s Office. Property Tax Exemptions
Homeowner Exemption
If the property is your primary residence, this reduces your EAV by up to $10,000,8Cook County Treasurer’s Office. Homeowner Exemption worth roughly $950 a year for a typical Cook County homeowner.7Cook County Assessor’s Office. Property Tax Exemptions Once approved, it auto-renews.
Senior Exemption
Owners aged 65 or older who occupy the home get an additional EAV reduction on top of the Homeowner Exemption. It auto-renews after the first application.9Cook County Assessor’s Office. Senior Exemption
Senior Freeze
The Senior Freeze locks your EAV at the level from the year you first qualified. Requirements: age 65 or older, ownership and occupancy, and household income of $65,000 or less. The income cap rises to $75,000 starting with Tax Year 2026, showing up on bills in 2027.10Cook County Assessor’s Office. Assessor Kaegi Praises Passage of Property Tax Relief for Senior Homeowners The freeze locks the EAV, not the total bill; if rates rise, so can your payment.11Cook County Assessor’s Office. Low-Income Senior Freeze Exemption
Persons With Disabilities Exemption
A $2,000 annual EAV reduction for homeowners with a disability. Recent state legislation made it auto-renewing, so a one-time filing is enough.12Illinois General Assembly. Illinois Code 35 ILCS 200/15-168 – Persons With Disabilities Homestead Exemption
Veterans With Disabilities Exemption
Veterans with a service-connected disability certified by the U.S. Department of Veterans Affairs get EAV reductions scaled to the disability rating:13Illinois General Assembly. Illinois Code 35 ILCS 200/15-169 – Veterans With Disabilities Exemption
- 30% to 49% disability: $2,500 EAV reduction
- 50% to 69% disability: $5,000 EAV reduction
- 70% or higher: the first $250,000 of EAV is fully exempt from property taxes
Surviving spouses of veterans whose deaths were service-connected also qualify for the full $250,000 exemption. This exemption does not auto-renew. You must file every year.
How to Pay
The Treasurer accepts payment through several channels, and fees vary.
- Electronic check on the Treasurer’s website: no processing fee. This is the cheapest option.
- Credit or debit card online: a 2.1% convenience fee goes to the payment processor, not the county.14Cook County Treasurer’s Office. Guide to Property Tax System
- Chase Bank in person: any Illinois branch, no extra fee. Bring the original tax bill or the bank won’t process the payment.15Cook County Treasurer’s Office. Pay at Chase Bank
- Mail: send a check with the payment coupon to the P.O. box printed on the bill. Allow lead time for delivery.
- Treasurer’s downtown office at 118 North Clark Street: in person, with an immediate receipt.
Online and Chase payments usually post to the county’s system in two to five business days. Keep the confirmation number or stamped receipt for at least seven years in case a payment dispute comes up during a refinance or sale.
If You Think Your Assessment Is Too High
You get two shots at an appeal each cycle, and you can use both. The first is with the Cook County Assessor, which opens township-specific appeal windows on a rolling schedule.6Cook County Assessor’s Office. Assessment and Appeal Calendar Even if your township isn’t being reassessed, you can still appeal when its window opens.
The strongest evidence is comparable properties: similar homes nearby that sold for less than what your assessment implies your home is worth. The Assessor’s online appeal tool has a built-in search for comparables.16Cook County Assessor’s Office. File an Appeal Online Corrections to recorded characteristics like square footage, room count, or building age can be submitted year-round without waiting for the appeal window.
If the Assessor’s decision disappoints, the Cook County Board of Review provides a second round of appeals on its own township schedule. It operates independently, so a fresh set of eyes reviews your case. Some homeowners skip the Assessor stage and file directly with the Board of Review; filing with both gives you two chances at a reduction.
If You Don’t Pay
Unpaid property taxes generate interest at 0.75% per month, and if the balance stays delinquent, the Treasurer offers those unpaid taxes at the Annual Tax Sale.17Cook County Treasurer’s Office. Annual Tax Sale A tax buyer pays what you owe and receives a tax lien certificate. You still own the property, but you now owe the buyer, and the payoff includes substantial penalties on top of the original tax.
After the sale, you have a redemption period to clear the lien through the Cook County Clerk’s office. For most residential properties it’s two and a half years. For vacant land, buildings with seven or more residential units, and commercial or industrial properties, it’s one year. Miss the redemption window and the tax buyer can petition for a deed to the property.18Cook County Treasurer’s Office. If Taxes Were Sold If your taxes have already been sold, talk to a lawyer quickly. Every month adds cost and shrinks your options.