Illinois property tax rates by town vary more than almost any state in the country, with aggregate rates in some municipalities exceeding 10% of assessed value while others stay below 5%. The statewide average effective rate sits near 1.9% of home value, roughly double the national median, but that number hides enormous local variation. A homeowner in one suburb can pay two or three times what someone a few miles away pays, because each town’s rate is built from the ground up out of overlapping local taxing districts and the property wealth inside their boundaries.
Why Rates Swing So Much Between Towns
Three things decide whether your town has a high rate or a low one: how much taxable property sits inside each district’s boundaries, how many districts overlap at your address, and how much those districts are spending.
A town anchored by a major corporate campus or shopping center benefits from commercial property shouldering a big share of the base. That spreads the cost across more value and pushes individual homeowner rates down. A bedroom community with little commercial property has to fund the same services (schools, roads, fire protection) almost entirely from residential taxpayers, which drives the rate up. High home values alone don’t guarantee low rates. What matters is whether total assessed value is large enough relative to total levies.
Cook County adds a distinctive wrinkle. It’s the only county in Illinois that classifies property by type and applies different assessment levels. Residential property is assessed at 10% of market value, while commercial and industrial property is assessed at 25%.1Cook County Assessor’s Office. Classifications of Real Property Every other county uses a flat 33 1/3% for all property types. This classification shifts more of the burden toward business property in Cook County, which is one reason rate dynamics between Chicago-area towns and downstate communities look so different.
The collar counties (DuPage, Lake, Will, Kane, and McHenry) tend to have strong residential and commercial bases, but rates still swing widely between individual municipalities depending on which school districts serve them. Downstate towns often face a compounding problem: lower property values require higher rates to generate the same revenue, and those higher rates can discourage new development, keeping values low.
What’s Actually in Your Rate
The rate printed on your tax bill isn’t set by one government. It’s the combined total of every taxing district serving your address, sometimes a dozen or more stacked on top of each other. Each operates independently with its own budget and levy authority.
School districts dominate. Statewide, roughly 63% of all property tax revenue goes to fund schools. In the collar counties, that share climbs closer to 70%.2Illinois Department of Revenue. What Is Property Tax and How Is It Collected and Distributed This means the single biggest factor in whether your town has a high or low rate is often which school district you’re in and how that district is funded. Two homes on the same block can get different tax bills if a school district boundary runs between them.
Beyond schools, your rate reflects contributions from your municipality, township, county, park district, library district, fire protection district, community college district, and sometimes special service areas or sanitary districts. Each of these calculates its own levy independently. A library board deciding to expand doesn’t need permission from the fire district. It just adds to the total. The composition of overlapping districts at your specific address is what makes your rate unique.
How the Rate Is Built
Every property tax rate in Illinois starts with a simple division. Each local government body submits a levy to the county clerk, which is the total dollar amount that body needs for its budget. The clerk then divides each levy by the total equalized assessed value of all taxable property within that body’s boundaries to produce a rate per $100 of assessed value.3Justia Law. Illinois Code 35 ILCS 200 – Title 6 Levy and Extension When property values rise and the levy stays flat, the rate drops. When a government needs more money but the base hasn’t grown, the rate climbs.
Assessed value in Illinois isn’t what your home would sell for. By statute, most property is assessed at 33 1/3% of its fair cash value.4Illinois General Assembly. Illinois Code 35 ILCS 200/9-145 – Statutory Level of Assessment A home worth $300,000 on the market would carry an assessed value around $100,000. The tax rate is applied to that assessed figure, not the market price, which is why Illinois rates look deceptively high when quoted as a percentage.
The Illinois Department of Revenue adds another layer by applying a state equalization factor (the multiplier) to each county’s assessments. The county clerk uses this multiplier to bring the county’s overall assessment level in line with the statutory one-third standard.5Illinois General Assembly. Illinois Code 35 ILCS 200/18-40 – Application of Equalization Factor If a county has been assessing property at 28% of market value instead of 33 1/3%, the multiplier bumps those values up.
Finding Your Town’s Exact Rate
The county clerk is the official responsible for calculating and publishing tax rates in each county. Once all levies are submitted and the state multiplier is applied, the clerk extends the taxes and produces rate reports for every taxing district.6Cook County Clerk. Tax Extension and Rates These annual reports break down the composite rate for every township and municipality and show exactly how much each overlapping district contributes.
Most county clerks publish this data online. Cook County, for example, maintains annual Tax Rate Reports going back to 2004 on the clerk’s website. You can also look up your specific property through county property tax portals by entering your 14-digit Property Index Number. These portals show your assessed value, the tax rate and tax code assigned to your location, and a breakdown of which districts receive your tax dollars.7Cook County Property Tax Portal. Cook County Property Search DuPage, Lake, Will, and the other collar counties offer similar search tools through their respective clerk or treasurer websites.
If you’re comparing towns before buying a home, don’t just compare composite rates. Pull the actual dollar amount on recent bills for comparable properties. A town with a high rate and low assessments can produce a smaller bill than a town with a moderate rate and aggressive assessments. The rate alone never tells the full story.
What Limits Rate Growth: PTELL
Illinois limits how fast most taxing districts can grow their levies through the Property Tax Extension Limitation Law, widely known as PTELL or simply the tax cap. For districts subject to PTELL, total taxes extended on existing property cannot increase by more than 5% or the prior year’s Consumer Price Index increase, whichever is less.8Illinois General Assembly. Illinois Code 35 ILCS 200/18-185 New construction and voter-approved increases are the main exceptions.9Illinois Department of Revenue. What Is the Property Tax Extension Limitation Law (PTELL)
PTELL does not cap your individual tax bill. If your property’s assessed value rises faster than your neighbors’ values, your share of the total levy grows even while the district’s overall extension stays within the cap. The law constrains the taxing district’s total take, not your personal obligation. Home rule municipalities can opt out of PTELL entirely, which is why some cities face fewer constraints on rate growth.
Lowering What You Actually Pay
You can’t vote your town’s rate down from the kitchen table, but two mechanisms directly reduce your bill: exemptions that shrink the assessed value the rate applies to, and appeals that challenge the assessed value itself.
Illinois exemptions include the General Homestead Exemption (up to $10,000 off EAV in Cook County, $8,000 in collar counties, $6,000 elsewhere), the Senior Citizens Homestead Exemption (an additional $8,000 in Cook and collar counties, $5,000 elsewhere), the Senior Freeze (which locks assessed value for qualifying seniors with household income of $75,000 or less in 2026), and the Disabled Veterans Exemption (sliding scale from $2,500 up to $250,000 off EAV depending on service-connected disability rating).10Illinois Department of Revenue. Property Tax – Exemption Information (PIO-74)11Cook County Assessor’s Office. Veterans with Disabilities Exemption Exemptions require applications filed with your local assessor’s office. They don’t transfer from the previous owner when you buy a home, and missing them is one of the most expensive mistakes Illinois homeowners make.
If your assessed value looks high compared to recent sales of similar homes or to assessments on comparable neighboring properties, you can appeal. The first step is a complaint to your county’s Board of Review, generally within 30 days after the annual assessment roll is published in local newspapers. If that’s denied, you can escalate to the state Property Tax Appeal Board within 30 days of the Board of Review’s written decision.12Property Tax Appeal Board. Filing Your Appeal Deadlines are tight, and missing one means waiting another assessment cycle to try again.