How does Illinois assess property?

Illinois taxes the equalized assessed value (EAV), not market value. Most counties assess at 33.33% of fair market value; Cook County assesses residential property at 10%. A state equalization factor then adjusts the assessed value to reach the EAV.

What is the homestead exemption?

The general homestead exemption reduces the EAV of an owner-occupied primary residence before the tax rate is applied — typically 6,000 dollars in most counties and up to 10,000 dollars in Cook County. It lowers your taxable value, not the rate.

Why does Illinois have such high property taxes?

Illinois has one of the highest effective property tax rates in the country, around 2% of market value, because it relies heavily on local property tax to fund schools and local government rather than on a high income tax.

What is a composite tax rate?

The composite (or aggregate) tax rate is the sum of all overlapping taxing-district rates — schools, county, municipality, parks, libraries — expressed as a percentage of EAV. It varies widely by location, often between 7% and 12% of EAV.

How accurate is this estimate?

It is a close estimate using typical county assessment ratios and composite rates plus the general homestead exemption. Your actual bill depends on local rates, the current equalization factor, and additional exemptions like senior or disability relief.

Illinois Property Tax Estimator

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Illinois has among the highest effective property tax rates in the United States — roughly 2% of a home’s market value each year. The way Illinois reaches that figure is unusual: rather than taxing market value directly, it taxes the equalized assessed value (EAV), applies a state equalization factor, subtracts homestead exemptions, and only then multiplies by a local composite tax rate. This estimator walks through every step so you can see where your bill comes from.

How it works

The calculation follows the Illinois EAV chain:

Assessed value. Most counties assess at 33.33% of fair market value (assessed = market × 0.3333). Cook County assesses residential property at 10% instead.
Equalized assessed value (EAV). The state multiplier (equalization factor) is applied. Outside Cook County this is usually near 1.0; in Cook County it is much higher to align with the statewide one-third standard.
Exemptions. The general homestead exemption is subtracted from the EAV for an owner-occupied home, giving the taxable EAV.
Tax. The local composite rate is applied: tax = taxable EAV × composite rate.

Tips and example

For a $300,000 home in a typical downstate county assessed at 33.33% with a composite rate of about 8% and a $6,000 homestead exemption: the assessed value (and EAV) is $100,000, the taxable EAV is $94,000, and the annual tax is roughly $7,520 — about 2.5% of market value.

Cook County works differently: a $300,000 home is assessed at 10% ($30,000), then multiplied by the county equalization factor (often around 3.0) to reach an EAV near $90,000, before the homestead exemption and local rate apply. Use the Cook County preset to model that path. This is an estimate — senior, senior-freeze and disability exemptions can lower your bill further.