Appealing your property tax after buying a home

Your purchase price and the Assessor's value

New owners often notice that the Assessor's estimate of market value is not the same as what they paid. The Assessor explains why: a recent purchase price is sometimes, but not always, a reflection of true market value. Sale prices depend on the home itself, but also on the individual buyer and seller and even the time of year. To be fair to homes that sold recently and homes that did not, the Assessor uses the same methods to estimate value for all of them.

So a different number on your notice is not an error by itself. But if you paid less than the Assessor's market value in an ordinary sale, your purchase can support an appeal based on overvaluation. The Assessor lists overvaluation as one of the most common reasons to appeal, alongside uniformity and incorrect property information, and encourages filers to submit supporting documents such as recent closing statements.

The 2-year disclosure rule

The Assessor's appeal rules say filers must disclose the purchase date and purchase price of the property if the purchase took place within two years of the lien date (January 1) of the appeal year. The rule applies whether or not your appeal is based on the purchase price, and whether or not the sale was arm's length. All relevant purchase documents must be submitted too.

In practice this means you cannot leave a recent purchase out of an appeal, even if you argue on comparable homes instead. If your price was above the Assessor's value, plan your appeal with that in mind.

Documents to gather

Under the Assessor's Rule 13 for recently sold properties and purchase-price appeals, filers must provide:

• the purchase price and purchase date;
• all relevant purchase documents, such as the Purchase and Sale Agreement, the Deed and the Closing Statement;
• the identities of the buyer and the seller, and any relationship between them;
• if you say the price included personal property (for example furniture), the PTAX-203 transfer declaration or an affidavit with the same information.

The Assessor also strongly encourages including the PTAX-203 with any appeal based on purchase price. If the sale price is far above or below the Assessor's current value, the rules ask for an affidavit explaining the circumstances of the sale: earlier offers, time on the market and the reasons for the sale. Short sales, foreclosures and bank-owned (REO) sales need an appeal brief with the details and supporting papers such as court orders.

For photos, the rules require a photograph of the front of the property for Assessor appeals, except for individual taxpayers filing on their own for their own residence. All supporting documents must be filed together with the appeal, before your township's closing date.

At the Board of Review

You can also take a recent purchase to the Board of Review when your township opens there. The Board of Review's guide for taxpayers says that if you bought your home in the past 3 years in an arm's length transaction for less than the Assessor's current market value, you can use your closing documents as evidence to support a reduction. It also lists recent sales of similar homes, within the last 3 years, as market evidence.

Individual taxpayers may represent themselves at the Board of Review. See Assessor vs Board of Review for how the two steps fit together.

Apply for the homeowner exemption

The homeowner exemption is separate from an appeal, and new owners should check it right away. According to the Assessor, most homeowners qualify if they own and occupy the property as their principal place of residence. It reduces the equalized assessed value of the home by $10,000; the Assessor notes this is not the dollar amount your bill goes down. Once applied, it renews automatically each year.

Eligibility is tied to January 1 of the tax year: you must own the home (or be responsible for its taxes) and live in it as your principal residence on that date. If you bought a newly built home that was not ready to move into until after January 1, the Assessor says the exemption is prorated.

To see what is applied to your home, open its Property Details on the Assessor's site and review the Exemption History and Status section. If the normal filing period has ended, the Assessor processes homeowner exemption applications as Certificates of Error. See Cook County exemptions and Certificates of Error for missed exemptions.

Your first bills as a new owner

The Board of Review explains that the first installment bill is, by law, 55% of the previous year's total bill. It is not based on this year's assessment. The second installment cannot be calculated until the Board of Review has finished its review of every appeal in all 38 townships for that tax year.

That is why changes show up late. The Assessor says exemptions appear on the second installment bill, and that changes from a reassessment show on the second installment bill the year after the reassessment. Your bill also depends on exemptions, the assessed value of your whole community and local levies, not on your assessment alone.

Before you file

Check your township's 2026 Assessor and Board of Review windows on deadlines by township, collect your closing papers, and confirm your homeowner exemption. A free check of your home against similar homes can show whether your assessment looks out of line. Any appeal can end with no change.