Between December 2024 and November 2025, the Cook County Assessor's Erroneous Exemptions department worked more than 1,400 cases and collected $6.7 million. Of that, $4.4 million went back to local taxing districts.
These are back bills for exemptions a property should not have had. The owner moved out, rented the house, claimed a second home, or a parent died and the exemptions kept renewing. Homeowner and senior exemptions renew on their own each year, so nothing stops them unless someone acts.
The bill can reach back three or six years, with interest and sometimes a 50% penalty. You can stop it from growing by removing the exemption yourself.
Quick Answer
When the Assessor finds an exemption on a property that did not qualify, it sends a Notice of Discovery, then a Notice of Intent to Record a Lien. With one or two wrong exemptions, the law lets it bill the three bill years before the notice year, plus 10% interest a year. With three or more, it can go back six bill years and add a 50% penalty. Pay within 30 days of the lien notice and no lien is filed; after a lien, the debt grows 1.5% a month. You can ask for a hearing within 30 days of the lien notice. The cheapest fix is the Assessor's free Exemption Removal Waiver, filed as soon as a home stops qualifying.
When an exemption becomes "erroneous"
Homestead exemptions are for your main residence on January 1 of the tax year. The Assessor says each person gets one homestead exemption, on one primary residence, per tax year. An exemption the property did not qualify for is what the Assessor calls an erroneous exemption.
- You moved out or rented the house. The exemption is wrong from the first January 1 you no longer lived there.
- You have a second home. Only one home can carry your homestead exemption.
- A parent died. The Assessor says the home still qualifies for the year of death if the parent lived there on January 1 of that year. From the next January 1, the exemptions are wrong unless a qualifying owner lives there.
- Income went over the limit. The Senior Freeze and the Longtime Homeowner Exemption have income limits. The Assessor names households over the limits among its most common findings.
How the Assessor finds them
The Assessor's audits look for exemptions on more than one property, households over the income limits, and owners who have died. It also takes tips through a reporting form on its Erroneous Exemptions page. In 2022 it reported collecting more than $15 million over the three years before.
- Notice of Discovery. It comes by regular and certified mail. It means an audit has started, not that you owe. You can send the Assessor information for the audit.
- Notice of Intent to Record a Lien. If the audit finds wrong exemptions, this notice lists each one, the years and the amounts due. The law requires it within three years of the Notice of Discovery. If the audit clears you, the Assessor tells you in writing.
How far back, and what it costs
The law counts wrong exemptions in a specific way. One type of exemption on one property counts once, no matter how many years it ran. A homeowner and a senior exemption on the same house are two. Add a Senior Freeze and it is three. The same exemption on two houses is two.
| Wrong exemptions | How far back | What you owe |
|---|---|---|
| 1 or 2 | The 3 bill years before the year of the notice | The tax that should have been billed, plus 10% interest a year |
| 3 or more | The 6 bill years before the year of the notice | The tax, plus a 50% penalty, plus 10% interest a year |
| After a lien is recorded | Due within 30 days, then 1.5% a month |
A "bill year" is the year the bills are paid. Cook bills run a year behind, so bills paid in 2025 are for tax year 2024. A notice in 2026 can reach bills paid in 2023 through 2025 (tax years 2022 through 2024), or 2020 through 2025 with three or more wrong exemptions.
A worked example built on the record. In tax year 2024, the median homeowner exemption on a Cook County home was worth about $842 on the bill, and the median senior exemption about $682. Say a parent died in 2022 and both kept renewing. A 2026 notice counts two wrong exemptions and reaches three bill years: about $1,524 a year, or about $4,572, before interest.
Had the house also kept a Senior Freeze (median value about $2,419 a year), it would be three exemptions: six bill years plus the 50% penalty. The Freeze must be refiled every year, so it usually drops off after a death unless someone keeps filing it.
Honest mistakes and fraud
The law sets how far back the Assessor can go by the number of wrong exemptions, not by why they happened. An honest mistake with three exemption types still reaches six years and carries the penalty. A few rules do turn on the circumstances:
- The Assessor's own error. If a clerical mistake by the Assessor's office caused it and you paid your bills as they came, you owe the tax but no interest or penalty.
- Inherited homes. A spouse, child, grandchild, brother, sister, niece or nephew who inherited the home is not charged the penalty on a senior exemption for years it renewed without an application. Interest still applies.
- Fraud. Senior Freeze and Longtime Homeowner applications are signed under penalty of perjury. State law says signing a fraudulent one is perjury, a separate matter from the back bill.
How to fix it yourself before a notice arrives
- Look up every PIN you own or manage. The Assessor's property search lists each exemption under Exemption History and Status.
- File the Exemption Removal Waiver. The Assessor's free form, online or on paper, lists the exemptions you no longer qualify for, by tax year and PIN.
- Beat the March 1 date. If the home was not your main residence on January 1 of a tax year, state law says the Assessor must receive your notice by March 1 of the year those bills are paid. Move out during 2025, and the deadline for tax year 2026 is March 1, 2027. On time means no exemption that year, and if the Assessor fails to remove it, no interest or penalty. Keep proof: certified mail with a return receipt, a date-stamped copy, or the online confirmation.
- Use the reassessment grace period. In a reassessment year, you have 60 days after receiving your assessment notice to tell the Assessor about a wrong exemption from a past year. Pay the tax plus interest and you owe no penalty. The south and west suburbs were reassessed for tax year 2026; Chicago is reassessed for tax year 2027.
- Already have a notice? Send proof that you qualified, such as documents showing you lived there. Pay within 30 days of the lien notice to avoid a lien, or ask for a hearing within 30 days. A hearing officer decides, and that decision can go to the circuit court.
Selling? The lien does not bind a good-faith buyer who bought before it was filed without notice of the problem, but clearing the bill before closing is simpler. See the seller's bill and the buyer's bill for exemptions in the year of a sale.
Where Censum fits
Censum's free exemption check shows which exemptions are on a PIN's record. Run it on every Cook County property you own or look after for a family member. Removing an exemption takes only the Assessor's free form; you do not need Censum for that. If the check shows a home is missing an exemption it did qualify for, Censum can prepare the Assessor's refund filing for past years, explained in our guide to refund filings versus appeals.
The numbers behind this article
The $6.7 million, 1,400 cases and $4.4 million are from the Assessor's January 23, 2026 news release (December 2024 through November 2025). The $15 million is from its January 19, 2022 release. Median exemption values are Censum's tabulation of tax year 2024 PIN-level exemption amounts in PTAXSIM, the Cook County Assessor's Office research database built from Clerk and Treasurer records, among the 1,005,437 PINs with a homeowner exemption: each exemption amount times the PIN's total tax-code rate. The Assessor describes PTAXSIM results as not official. Look-back periods, interest, penalty and deadlines are from the state law listed below.
FAQ
I moved out but still own the house. Can the homeowner exemption stay on?
No. It is wrong from the first January 1 you did not live there. File the removal form for that tax year.
My parent died. When do the exemptions have to come off?
The year of death is fine if your parent lived there on January 1. Remove them for the next tax year unless a qualifying owner lives in the home.
Can I avoid the interest and penalty?
Sometimes. A notice that reaches the Assessor by March 1 of the bill year avoids both for that year. The 60-day reassessment grace period avoids the penalty. An error by the Assessor's office avoids both.
Is there a fee to remove an exemption?
No. The Exemption Removal Waiver is free.
Sources
- Cook County Assessor, Erroneous Exemptions
- Cook County Assessor, Exemption Removal Waiver
- Cook County Assessor, Senior Exemption (year-of-death rules)
- Cook County Assessor, Homeowner Exemption
- Cook County Assessor, Senior Freeze Exemption
- Cook County Assessor, Longtime Homeowner Exemption (perjury and audit warning)
- Cook County Assessor, news release of January 23, 2026 (2025 results)
- Cook County Assessor, news release of January 19, 2022 ($15 million collected)
- Illinois Property Tax Code, 35 ILCS 200/9-275 (erroneous homestead exemptions)
- Illinois Property Tax Code, 35 ILCS 200/15-175 (general homestead exemption; subsection (d-1) on the March 1 notice)
- Illinois Property Tax Code, 35 ILCS 200/15-172 (Senior Freeze; perjury warning)
- Illinois Property Tax Code, 35 ILCS 200/15-177 (long-time occupant homestead exemption; perjury warning)
- Censum tabulation of tax year 2024 PIN-level exemption amounts and tax code rates from PTAXSIM (Cook County Assessor's Office), run November 11, 2026.
Sources accessed November 11, 2026.
Next step
Run the free check on every Cook County property you own and remove anything that no longer fits. Check my exemptions
Censum LLC is a data and analytics company, not a law firm and not a tax advisor. Censum is independent and is not affiliated with Cook County or any government agency.