Cook County property tax calculator

How the calculator works

The calculator above asks for four things:

• Assessed value from your Assessor notice or your PIN page. For most homes this is 10% of the estimated market value.
• Tax rate (%) from your second-installment tax bill.
• Homeowner exemption: yes or no. Yes subtracts $10,000 of equalized assessed value.
• Senior exemption: yes or no. Yes subtracts another $8,000 of equalized assessed value.

It then multiplies your assessed value by the 2025 state equalizer, 3.0300, subtracts the exemptions you picked, and applies your tax rate. The result is an estimate, not your bill.

The formula, line by line

The equalizer is a multiplier set each year for Cook County by the Illinois Department of Revenue. For tax year 2025 the tentative figure in April 2026 was 2.8683, and the final figure issued on June 18, 2026 is 3.0300.

The Cook County Clerk's history shows 3.0163 for 2023, 3.0355 for 2024 and 3.0300 for 2025. The Clerk describes the 2025 change as a decrease of 0.18%.

The tax rate comes from the Clerk. Each taxing district (schools, city or village, county, parks and others) files a levy, and the Clerk works out the rate needed to raise it from all taxable property in the district.

Your bill uses one combined rate for your 5-digit tax code, which adds up the rates of every district you live in. The Clerk's 2025 file has 4,536 tax codes.

A worked example

These are round, made-up numbers for illustration only. Example: a home with an assessed value of $25,000, a tax rate of 7.000% and the homeowner exemption.

If the same example owner also had the senior exemption, taxable EAV would be $57,750 and the estimate $4,042.50.

Notice that a $10,000 exemption does not take $10,000 off the bill. The Assessor explains that your savings equal the exemption amount times your local tax rate, so $700 in this example.

Where to find your numbers

• Assessed value: on your Assessor notice, or on your property's page at the Assessor after an address search.
• Tax rate: printed on your second-installment bill. The Assessor notes it is set each year by the Cook County Clerk.
• Tax code: shown on your Assessor PIN page as "Taxcode."
• Past bills and exemptions: the Treasurer's property tax overview lets you download a copy of your bill and check your exemptions.

How much rates differ across the county

Tax rates vary a lot by location, so always use the rate from your own bill. In the Clerk's 2025 file, the combined rates range from about 1.76% to 35.78%, with a median of about 8.74% across tax codes.

One Chicago tax code, 76001, had a 2025 rate of 6.853152%. A Barrington tax code, 10001, had 6.856574%.

Range and median: our calculation from the Cook County Clerk's 2025 tax code agency rate file. The median is across tax codes, not across homes.

What the calculator leaves out

The calculator covers the two most common exemptions. It does not include:

• the Senior Freeze, which freezes EAV for eligible seniors with household income of $65,000 or less and must be filed every year;
• the persons with disabilities exemption ($2,000 of EAV);
• veterans with disabilities ($2,500 or $5,000 of EAV by rating, up to $250,000 at 70% or more) and returning veterans ($5,000 of EAV);
• the longtime homeowner exemption, which caps EAV growth for qualifying owners;
• the home improvement exemption, which shields up to $75,000 of added market value for four years.

It also cannot predict next year. The equalizer for tax year 2026 has not been announced, and the Assessor notes that tax rates are calculated each year and can change.

Your first-installment bill is not calculated this way at all. By law it is 55% of the previous year's total bill.

See our exemptions guide for who qualifies for what.

Common mistakes when estimating

• Entering market value instead of assessed value. For most homes, assessed value is 10% of market value. Typing the market value makes the estimate about ten times too high.
• Entering the rate the wrong way. The calculator wants a percent. A rate shown as 6.853 means 6.853%, not 0.06853%.
• Using the first installment as a check. The first installment is 55% of last year's total, so compare the estimate with a full year: both installments added together.
• Claiming an exemption you do not have. Check your bill or the Treasurer's site first. If one is missing but you qualified, see our missed exemption guide.
• Mixing years. The equalizer and rates here are for tax year 2025. Using them with a 2026 value gives a rough guide, not a forecast.

Using the estimate to think about an appeal

You can use the calculator to see roughly what a different assessed value would mean. In our example, an assessed value $2,500 lower would cut EAV by $7,575, which at 7.000% is about $530.

Real results could be smaller. The Assessor explains that a change in your assessment does not lead to the same change in your taxes, because your share of the community's total value and local levies also matter.

The Assessor's rule of thumb: if the facts on your record are correct and the market value is within 10 percent of what you think your home is worth, an appeal is unlikely to make a big difference. Appeals can also end with no change.

To see how your assessment compares with similar homes, check your home free. If you decide to appeal, you file it yourself, for free, on the county site. Our appeal guide shows how.