Lake County assessment notices have recently been mailed out for many homeowners. One line on the notice could be worth hundreds of dollars a year, and it's an easy one to miss.

I got my Lake County property tax assessment notice last week. The annual increase of my assessed value was the number that I immediately noticed, but there was one line I almost skipped right past.

We bought our house in Lake County in 2025. The prior owners had moved to Florida a few years before they sold, and once they stopped living in IL permanently, the exemption came off. The only reason I caught it is that I read the whole notice.

So I drove up to the township assessor's office, showed my driver's license and the prior year's tax return, and had it fixed in about ten minutes. While I was there, the woman helping me mentioned that this happens all the time, and not just after a sale. It can happen when people retitle their home into a trust and don't send in the trust paperwork when the county asks for it (typically, the trust documents need to show that you are a primary beneficiary of the trust).

If you own a home in Lake County or Cook County, here's what to look for and what to do about it.

What the exception actually does

Illinois assesses your home at one-third of what the county thinks it's worth. That number is your equalized assessed value, or EAV. Your tax bill is your EAV, minus any exemptions, multiplied by the combined rate for your school district, village, park district, etc.

The General Homestead Exemption (Lake County calls it that; Cook County calls it the Homeowner Exemption) knocks a fixed amount off your EAV before the rate gets applied.

Multiply that by your local tax rate and you get the annual savings. The Cook County Assessor puts the average at roughly $950 a year. Lake County varies by township, but it's real money either way. And it's money you're entitled to just for living in the house you own. There's no income test and no age requirement. If you live in it as your main home as of January 1, you get it.

Once it's on, it renews on its own in both counties. Which is why homeowners don't always think about it, and it can slip through the cracks.

Two ways it falls off without you noticing

1. You bought the house.

Exemptions don't automatically follow the property to a new owner. If the seller had one, it usually stays on for the year of the sale and then the county takes a fresh look. If the seller had already lost it, like mine had, there's nothing to carry over at all. The county will not assume you are entitled to the homestead exemption, and you will have to reapply.

Illinois law does require the assessor to mail the new owner a notice when the prior owner had an exemption. But that's one envelope, in the middle of the flood of mail you get after a move, and it's easy to toss.

2. You put the house in a trust.

This is the one that catches people who've been in the same home for twenty years. You do your estate plan, your attorney retitles the house into your revocable living trust, and the deed now says the trust owns the property instead of you.

The county sees a new owner on the deed. They send a letter asking you to prove you're a beneficiary of the trust. If that letter gets lost, or you assume it's junk, or you figure your attorney handled it, the exemption drops.

Both counties ask for the same thing: a copy of the pages of the trust agreement that show you're a beneficiary. Lake County notes this is usually in the first few pages of the trust document. You don't have to send the whole thing.

How to check right now

Lake County

1. Go to the Lake County tax portal at tax.lakecountyil.gov and look up your property by address or PIN.
2. Look at your most recent bill for the exemptions listed.
3. If you got your 2026 assessment notice in the mail, look at the "Homestead Exemptions on previous bill" box. If it's blank and you live there, you have a problem.

To fix it, apply through the Chief County Assessment Office's Smartfile E-Filing Portal at assessor.lakecountyil.gov. You'll need proof of residency, like a driver's license, and if the home is in a trust, those trust pages. There's no annual renewal once it's approved. Your township assessor's office can also walk you through it in person, which is what I did.

Cook County

1. Go to cookcountyassessor.com, search your PIN, and open your Property Details.
2. Scroll to "Exemption History and Status." It shows which exemptions you've received, year by year.
3. If the Homeowner Exemption is missing for a year you lived there, keep reading.

Cook County's normal filing window for the current year opens in the spring. Right now that window has closed, so new applications get processed as a Certificate of Error. That sounds bureaucratic, but it's good news: a Certificate of Error lets you claim the exemption for prior years you missed, generally going back at least three tax years. If you've been paying without the exemption since you retitled into your trust in 2023, you may be owed a refund, not just a fix going forward.

If your name isn't on the recorded deed because the house is in a trust, Cook County accepts the trust agreement as proof of tax liability.

While you have the notice out

If you're in Lake County, the same notice that shows the exemption also shows the value the county plans to tax you on. Every township has its own appeal window, 30 days from the date the township's assessments are published in the local paper. The final filing date is printed on your notice. If you think the county's fair cash value is higher than what your home would actually sell for, that's your window to say so. Your township assessor's office is the first call. The Board of Review is where the formal appeal goes.

Cook County works on a different calendar. The county reassesses one-third of its townships each year, and appeal windows open and close township by township throughout the year. Check the Assessor's site for your township's dates.

The other direction

One more thing, because it cuts both ways. If you inherited a parent's home, or you moved and kept your old place as a rental, or you moved out of state and still own an Illinois property, make sure it isn't still carrying a homestead exemption. Cook County in particular pursues erroneous exemptions, and a property that received one in error can be hit with a lien for back taxes and penalties.