In Illinois, the Equalized Assessed Value of your property is the figure local taxing bodies actually tax. It starts as the assessor’s estimate of your property’s assessed value, gets adjusted by a state-issued multiplier so counties stay on a level playing field, and then is reduced by any exemptions you qualify for. Multiply that final taxable number by the combined local tax rate and you have your bill.
The Three Steps From Market Value to Tax Bill
The Illinois property tax calculation moves through a predictable sequence. First, the township or county assessor sets an assessed value based on your property’s estimated fair market value. Second, the Illinois Department of Revenue applies an equalization factor to produce your EAV. Third, exemptions are subtracted to arrive at your taxable EAV. That taxable EAV is what gets multiplied by local tax rates.
Each step matters because an error anywhere upstream flows into the final bill. A square-footage mistake at the assessor’s desk, a missed exemption, or an outdated classification can all inflate what you owe.
Step One: Your Assessed Value
In the 101 Illinois counties outside Cook, the assessor takes your estimated fair market value and multiplies it by one-third (33 1/3%) to produce the assessed value.1Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 200-9-145 – Statutory Level of Assessment A home worth $300,000 on the open market gets an assessed value of about $100,000.
Cook County works differently. It uses a classification system with lower assessment percentages: residential properties and apartment buildings are assessed at 10% of fair market value, while commercial and industrial properties are assessed at 25%.2Cook County Assessor’s Office. Your Assessment Notice and Tax Bill The same $300,000 Cook County home starts at an assessed value of only $30,000. That lower starting number does not mean lower taxes, because the equalization step corrects for it.
One boundary worth noting: farmland is not assessed on market value at all. Illinois assesses farmland based on agricultural productivity, using soil types and crop-yield data from a University of Illinois study.3Illinois Department of Revenue. Farmland Assessments A field next to a growing suburb is not assessed on its development potential.
Step Two: The State Equalization Factor
Local assessors across 102 counties don’t always hit the one-third target perfectly. Some assess a bit high, others a bit low. Each year the Illinois Department of Revenue reviews each county’s overall assessment level and issues a multiplier called the equalization factor. A county assessing below one-third of market value gets a factor above 1.0000 to push assessments up. A county assessing too high receives a factor below 1.0000.4Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 200-17-25 – Application of Final Equalization Factor When a county’s aggregate assessments fall within 99% to 101% of the one-third target, the state leaves it alone and certifies a factor of 1.0000.5Illinois.gov. 2025 Gallatin County Tentative Multiplier Announced
The arithmetic is simple. Your assessed value multiplied by the equalization factor equals your EAV.6Illinois Department of Revenue. Publication 136 – Property Assessment and Equalization Assessed value of $100,000 times a factor of 1.05 produces an EAV of $105,000. Without this correction, a county that systematically under-assessed would shift its share of state-funded costs onto better-assessed counties.
Step Three: Exemptions Lower Your Taxable EAV
Your EAV is not the number multiplied by the tax rate. Illinois offers several homestead exemptions that subtract fixed dollar amounts from your EAV before taxation. The result is your taxable EAV. Applying for every exemption you qualify for is the single biggest lever most homeowners have.
General Homestead Exemption
If you own and occupy the property as your principal residence, the General Homestead Exemption reduces your EAV by up to $10,000 in Cook County, up to $8,000 in counties bordering Cook, and up to $6,000 in all other counties.7Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 200-15-175 – General Homestead Exemption Technically the amount equals the increase in your property’s EAV above its 1977 EAV, capped at those maximums; for almost any property built or significantly renovated since then, the increase well exceeds the cap and you receive the full reduction.
Senior Citizens Homestead Exemption
Homeowners aged 65 or older who occupy the property as a primary residence receive an additional reduction of up to $8,000 in Cook County and the contiguous counties, or $5,000 elsewhere.8Illinois Department of Revenue. Property Tax – Exemption Information This stacks on top of the General Homestead Exemption. A qualifying senior in Cook County could see up to $18,000 removed from EAV before tax rates apply.
Senior Citizens Assessment Freeze
Separate from the flat-dollar senior exemption, the Senior Citizens Assessment Freeze locks your EAV at its level from the year before you first qualified. If your EAV was $80,000 when you qualified and later rises to $95,000, you continue to be taxed on $80,000. For the 2026 tax year, the maximum household income to qualify is $75,000, an increase enacted by Public Act 104-0452. You must reapply every year and meet the income threshold each year to keep the freeze.
Homestead Exemption for Persons With Disabilities
Homeowners with a qualifying disability who occupy the property as their primary residence can receive a $2,000 annual reduction in EAV.9Justia Law. Illinois Code 35 ILCS 200-15-168 – Homestead Exemption for Persons With Disabilities Social Security disability benefits or an Illinois Person with a Disability Identification Card satisfy the eligibility requirement.
Veterans Exemptions
Two separate exemptions apply to veterans. The Returning Veterans’ Homestead Exemption provides a $5,000 EAV reduction for the tax year in which a veteran returns from active duty in an armed conflict.10Justia Law. Illinois Code 35 ILCS 200-15-167 – Returning Veterans Homestead Exemption The Veterans with Disabilities Homestead Exemption provides ongoing relief based on the veteran’s service-connected disability rating from the U.S. Department of Veterans Affairs:
- 30–49% disability: $2,500 EAV reduction
- 50–69% disability: $5,000 EAV reduction
- 70% or greater: $250,000 EAV reduction, which effectively eliminates property tax on most homes11Cook County Assessor’s Office. Veterans with Disabilities Exemption
Home Improvement Exemption
If you remodel, add a room, or rebuild after a catastrophic event, the increase in assessed value from that improvement can be shielded for four years. The exemption covers up to $75,000 in fair cash value of the improvement, which works out to a maximum $25,000 reduction in assessed value.8Illinois Department of Revenue. Property Tax – Exemption Information Some counties apply it automatically. Cook County requires a separate application.
From Taxable EAV to Dollars
Once every property in a taxing district has its taxable EAV, local taxing bodies decide how much money they need through a process called a levy. School districts, park districts, municipalities, and other local governments each submit a levy. The county clerk divides each levy by the total taxable EAV of all properties in that district to produce a tax rate.12Illinois Department of Revenue. PTAX-60 – Illinois Property Tax Rate and Levy Manual
Your bill is the sum of all those rates multiplied by your taxable EAV. A taxable EAV of $95,000 and a combined rate of 8% produces a $7,600 bill. Most Illinois properties sit inside a dozen or more overlapping districts, and school districts usually take the largest share.
One rule shapes how fast those levies can grow. The Property Tax Extension Limitation Law (PTELL) caps the annual increase in a taxing district’s total levy at the lesser of 5% or the prior calendar year’s Consumer Price Index increase.13Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 200-18-185 – Extension Limitation For the 2025 levy year (taxes payable in 2026), the CPI figure was 2.9%, so that is the cap. PTELL limits the dollars collected, not the rate. If EAV in a district falls, rates rise to produce the same levy. PTELL applies only in counties that have adopted it, and voter-approved bond referenda sit outside the cap.
Reading and Checking Your Numbers
Your assessment notice and tax bill lay out every figure in sequence: estimated fair market value, assessed value (one-third of market value outside Cook, 10% residential inside Cook), the equalization factor applied, the resulting EAV, each exemption granted, and the taxable EAV after exemptions.2Cook County Assessor’s Office. Your Assessment Notice and Tax Bill The bill itself then lists each taxing district’s rate and the dollars levied.
Check every line. Errors in square footage, lot size, or classification happen more often than people expect, and each one inflates your EAV. If an exemption you should receive is missing, contact your county assessor’s office. Several of the exemptions above are not applied automatically, and skipping the application means paying more than the law requires.
Challenging an EAV That Looks Too High
If the number itself seems wrong, you can appeal. The first stop is your county Board of Review. Outside Cook County, you have 30 calendar days after publication of the assessment list to file a complaint.14Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 200-16-55 – Complaints Cook County residents get at least 20 days after publication of the notice. Missing the deadline forfeits your right to contest that year’s assessment.
Valid grounds include overvaluation (your property is assessed higher than its market value supports) and lack of uniformity (your property is assessed higher than comparable properties nearby). Strong evidence usually means a recent appraisal, comparable sales, or documentation that the assessor’s property record is factually wrong. A home listed at 2,400 square feet that measures 2,000 is a factual error that justifies a reduction on its own. Many disputes resolve at the township assessor level before a formal complaint is ever filed.
If the Board of Review rules against you, you have 30 days from its written decision to escalate to the Illinois Property Tax Appeal Board.15Illinois Property Tax Appeal Board. Filing Your Appeal PTAB requires a completed form plus supporting evidence, including a grid analysis of comparable sales or assessments. A thin evidence package will be dismissed.