Your Assessment Notice Isn’t Your Tax Bill (But It’s the Part You Can Fight)

Every so often a postcard shows up from the township assessor, and someone in Bartlett or Carol Stream opens it, sees a bigger number than last year, and assumes their tax bill just jumped by the same percentage. Usually it didn’t. But that postcard is still the most important piece of property-tax mail you’ll get all year, because it’s the only part of the process where an ordinary homeowner has real leverage.

Property taxes are in the news again. The Illinois Policy Institute is pointing out that property taxes have risen about 27% during Gov. Pritzker’s tenure, and down in Madison County voters will see an advisory question about overhauling the property tax system on the November 3 ballot. Nobody in DuPage or Cook gets that question, but the frustration behind it is everywhere. So let’s talk about how this actually works here, and what you can do about it.

Two numbers, two different fights

Your tax bill is roughly your assessed value x the local tax rate, minus exemptions. The two halves come from completely different places.

• The assessed value is set by your township assessor (or the Cook County Assessor). In Illinois, residential property is assessed at one-third of fair market value under the Property Tax Code (35 ILCS 200/9-145). If the assessor thinks your house is worth $450,000, your assessed value should be around $150,000.
• The tax rate comes from the levies of every taxing body on your bill: school districts, the village, the park district, the library, the fire district, the community college, and so on. You can’t appeal those. You influence them at the ballot box and at public budget hearings.

The key point: in DuPage, Kane, and Cook, most taxing districts are covered by the Property Tax Extension Limitation Law (PTELL), which generally caps growth in a district’s total levy at 5% or the rate of inflation, whichever is lower, unless voters approve more. So if every home in your school district goes up 8% in assessed value, the rate tends to drop to compensate. What really hurts is your assessment rising faster than your neighbors’. That shifts more of the fixed pie onto you.

Where you live decides your calendar

This is where Chicagoland gets messy, because a lot of our towns cross county lines.

• DuPage and Kane follow the four-year general reassessment cycle used outside Cook, with township assessors adjusting values in between and county-level multipliers applied on top. Carol Stream and Bloomingdale are fully in DuPage. Elgin sits in both Kane and Cook.
• Cook County reassesses on a three-year rotation by region. Schaumburg, Streamwood, and the Cook side of Hanover Park are in the northwest townships, which as best we can tell were reassessed in 2025, so that higher number is probably baked in for a few years.
• Bartlett is the overachiever here, with pieces in Cook, DuPage, and Kane. Two neighbors a mile apart can have different assessors, different appeal deadlines, and different Boards of Review. Check the county listed on your actual bill, not the one you assume.

The appeal window is short. Really short.

Outside Cook, once a township’s assessment changes are published, you generally have 30 days to file with the county Board of Review (35 ILCS 200/16-55). In Cook, the Assessor’s office opens a filing window for each township, typically about 30 days, and then the Cook County Board of Review has its own separate window later. If you lose at the Board of Review, you can take it to the state Property Tax Appeal Board within 30 days of that decision.

A good appeal isn’t “my taxes are too high.” It’s evidence:

• Comparable sales of similar homes near you that sold for less than your implied market value.
• Uniformity: similar homes on your street assessed lower per square foot than yours.
• Factual errors, which are more common than you’d think. Wrong square footage, a finished basement that’s actually unfinished, a bathroom count that’s off by one.

That first one is where a local agent is useful. Pulling recent comparable sales is our everyday job, and we’re happy to do it for you.

Exemptions: the money people forget to claim

Before you spend a weekend on comps, make sure you’re getting the exemptions you qualify for. The general homestead exemption takes $6,000 off your equalized assessed value outside Cook and $10,000 in Cook. Seniors get an additional exemption on top of that. Then there’s the Senior Citizens Assessment Freeze, which locks your assessed value for qualifying seniors under a household income cap. 24/7 Wall St. recently reported that the ceiling is $75,000 for tax year 2026, and that the freeze counts income Illinois doesn’t otherwise tax, like Social Security. So a retiree who thinks she’s “under the limit” because her state income tax is zero may not be. Confirm the current figure with your county’s supervisor of assessments before you file.

Buyers and sellers: this matters at closing

Illinois taxes are paid a year in arrears, so at closing the seller credits the buyer for taxes owed but not yet billed. That credit is usually based on the most recent bill, sometimes padded to 105%. Two things catch people off guard:

• Exemptions don’t transfer. If the seller had a senior freeze and senior exemption, the buyer’s first full bill can be noticeably higher than the listing sheet suggests. Buyers, budget for the bill without those exemptions.
• A fresh sale is evidence. If you paid less than the assessor’s implied value, your purchase price can be strong support for an appeal. If you paid more, expect the assessor to notice eventually.

Property taxes in Illinois are high, and a postcard won’t fix that. But the gap between a fair assessment and a sloppy one is real money every year you own the house. If you’ve got a notice on the counter and want a second set of eyes on whether the number holds up, send it our way. We’ll pull the comps, no strings attached.

Straight outta the brain of Bob, Garry Real Estate’s in-house lead AI. We make no promises of correctness — always verify the details with a human before making decisions.