The Cook County tax rate depends on which tax you mean. Property tax composite rates range from about 7% in some north suburban townships to over 30% in parts of the south suburbs, applied to a property’s equalized assessed value. Sales tax runs as high as 10.25% in Chicago and generally falls between 8% and 9% in suburban communities. And every Cook County resident pays Illinois’s flat 4.95% individual income tax. Two homes with identical market values can produce property tax bills tens of thousands of dollars apart, based entirely on where they sit.
Why Property Tax Rates Vary So Widely
There is no single countywide property tax rate. Each parcel sits inside overlapping taxing districts, and the combined figure from all of them is called the composite rate. That rate is expressed as a percentage of your property’s Equalized Assessed Value (EAV), and it changes from one tax code to the next.
North suburban areas like Northfield carry composite rates near 7%. Some south suburban communities see rates above 30%. The gap exists because south suburban areas tend to have smaller tax bases funding the same categories of services, so rates have to climb higher to generate the needed revenue. A typical homeowner’s composite rate funds a school district, a community college, a park district, a library, a fire protection district, the county’s forest preserves, and general county and municipal government. Schools usually take the largest share.
The Cook County Clerk’s office publishes an annual Agency Tax Rate Report listing every taxing district and its individual rate. The 2024 report is the most recent available and can be downloaded as a spreadsheet from the Clerk’s website.1Cook County Clerk. Agency Tax Rate Reports
How Your Property Tax Bill Is Calculated
Your bill is the product of two numbers: your EAV and your local composite rate. Three steps get you from a market value to a bill.
Assessment and Classification
The Cook County Assessor estimates fair market value, then applies a classification percentage. Residential property is assessed at 10% of market value; commercial and industrial property at 25%.2Cook County Assessor. Definitions for the Classifications of Real Property A home the Assessor believes is worth $300,000 receives an assessed value of $30,000.
The State Equalization Multiplier
The Illinois Department of Revenue then applies an equalization factor, commonly called the multiplier, to bring Cook County assessments in line with the rest of the state.3Illinois Department of Revenue. Property Assessment and Equalization The final multiplier for tax year 2024 was 3.0355.4Illinois Department of Revenue. 2024 Cook County Final Multiplier Announced Multiplying assessed value by this factor produces the EAV. That $30,000 assessed value becomes an EAV of roughly $91,065.
Levy and Rate
Each taxing district submits a levy to the Cook County Clerk stating how much money it needs. The Clerk’s Tax Extension Unit divides each levy by the total EAV inside that district’s boundaries, producing a rate per $100 of taxable value.1Cook County Clerk. Agency Tax Rate Reports Illinois law can limit the result through statutory rate ceilings and tax caps that restrict annual growth in extensions. Your bill equals your EAV, after any exemptions, multiplied by the composite rate from every district covering your parcel.
Finding Your Own Rate
Every property in Cook County has a 14-digit Property Index Number (PIN) printed on tax bills, assessment notices, and closing documents.5Cook County Assessor’s Office. Where Do I Find My PIN Enter that PIN or your street address on the Cook County Treasurer’s website to pull up your bill.6Cook County Treasurer’s Office. Cook County Treasurer’s Office It lists every taxing district receiving a share of your payment and the rate each one charged. A downloadable PDF includes a year-over-year comparison so you can see what changed.
For a broader view, match the tax code shown on your bill to the Clerk’s downloadable rate file to confirm the districts and rates are correct.1Cook County Clerk. Agency Tax Rate Reports If your assessment itself seems too high, the Cook County Board of Review accepts appeals on a township-by-township schedule, with no attorney required.7Cook County Board of Review. Cook County Board of Review Home Page
Exemptions That Lower Your Bill
Exemptions subtract a fixed dollar amount from your EAV before the composite rate is applied. Some auto-renew; others require annual paperwork. Missing an application means paying more than you owe, sometimes for years.
Homeowner Exemption
Any owner-occupant using the property as a primary residence qualifies, and the exemption reduces EAV by $10,000.8Cook County Treasurer’s Office. Homeowner Exemption The Assessor’s office renews it automatically each year once it is on file.9Cook County Assessor’s Office. Property Tax Exemptions
Senior Citizen Homestead Exemption
Homeowners aged 65 or older who occupy the home as their primary residence receive an additional EAV reduction of up to $8,000.10Illinois Department of Revenue. Property Tax – Exemption Information (PIO-74) This one also auto-renews.11Cook County Assessor’s Office. Senior Exemption
Senior Citizens Assessment Freeze
Different from the standard senior exemption. The freeze locks your EAV at its level in the year you first qualify, preventing increases from rising property values. For tax year 2026, total household income must be $75,000 or less.10Illinois Department of Revenue. Property Tax – Exemption Information (PIO-74) Your bill can still rise if tax rates increase, but the assessed-value side stays flat. The freeze requires a new application every year.
Veterans With Disabilities
Veterans with a service-connected disability certified by the U.S. Department of Veterans Affairs receive EAV reductions based on their disability rating. A rating of 70% or higher brings a $250,000 EAV reduction, which in practice eliminates the property tax bill on most homes.12Cook County Government. Veteran Homeowner Exemptions File annually.9Cook County Assessor’s Office. Property Tax Exemptions
Persons With Disabilities
Non-veteran residents with disabilities may qualify by providing proof through medical records or Social Security documentation. Under recent state legislation, this exemption now auto-renews once applied.9Cook County Assessor’s Office. Property Tax Exemptions
Payment Dates and Late Penalties
Cook County property taxes are paid in two installments. The first installment for tax year 2025 was due April 1, 2026.13Cook County Treasurer’s Office. Due Dates It is estimated at 55% of the prior year’s total bill. The second installment reflects the current year’s actual rates and assessments and typically arrives later in the year. Check the Treasurer’s website for the current second-installment date, since Cook County has historically pushed that deadline by weeks or months depending on when the rate-setting process finishes.
Any balance unpaid after its due date accrues interest at 0.75% per month for tax year 2023 and later; earlier tax years carried a 1.5% monthly penalty.14Illinois General Assembly. 35 ILCS 200 – Property Tax Code At 0.75% monthly, a $10,000 unpaid balance generates $75 in penalties each month.
Sales Tax Rates
Illinois charges a base sales tax of 6.25% on general merchandise statewide.15Illinois Department of Revenue. What Is Significant About Retail Sales of Qualifying Drugs and Medical Appliances Cook County layers additional taxes on top. In Chicago, the combined rate reaches 10.25%, one of the highest in the country: 6.25% state tax, 1.75% in Cook County taxes, Chicago’s 1.25% home rule tax, and a 1% Regional Transportation Authority tax.16Illinois Department of Revenue. Mass Transit District Sales Tax Suburban Cook County communities with their own home rule taxes typically land between roughly 8% and 9%, while unincorporated areas without a municipal layer generally fall closer to 8%.
Reduced Rate for Drugs
Prescription and non-prescription drugs are taxed at a reduced state rate of 1% instead of 6.25%.15Illinois Department of Revenue. What Is Significant About Retail Sales of Qualifying Drugs and Medical Appliances Locally imposed transit taxes can still apply on top of that 1%.
Grocery Tax Change in 2026
Starting January 1, 2026, Illinois eliminated its 1% state sales tax on qualifying grocery items. The same law authorized municipalities and counties to impose their own 1% local grocery tax by ordinance. Where a local government adopted that tax, the grocery rate stayed the same. Where it did not, groceries became tax-free at the state level. The RTA’s additional tax on grocery sales within its territory remains in effect regardless of local action.17Illinois Department of Revenue. FY 2026-11 Municipal and County Grocery Occupation Tax Rate Prepared food sold for immediate consumption, such as restaurant meals, stays subject to the full combined rate.
Illinois Income Tax
Every Cook County resident pays Illinois’s flat individual income tax of 4.95% on net income.18Illinois Department of Revenue. Income Tax Rates Unlike the federal system’s graduated brackets, Illinois applies the same rate to all income levels. This rate has been in effect since July 2017.
Federal SALT Deduction Cap
Cook County’s heavy property and sales tax load makes the federal State and Local Tax (SALT) deduction especially relevant. For tax year 2026, taxpayers who itemize can deduct up to $40,400 in combined state and local income, sales, and property taxes ($20,200 for married filing separately). The cap phases down for filers with modified adjusted gross income above $505,000 but will not drop below $10,000. Many Cook County homeowners pay well over $10,000 in property taxes alone, so a meaningful share of their local tax burden produces no federal benefit.