Illinois Residential Property Tax: Bills, Exemptions, and Appeals

Illinois residential property tax works on a pay-in-arrears system built around three numbers: your home’s assessed value, a state equalization factor, and the combined rates set by every local taxing district that covers your address. The bill you get this year is for last year’s taxes, and the total is calculated by turning your home’s market value into an Equalized Assessed Value (EAV), subtracting any exemptions you qualify for, and multiplying what remains by the sum of every overlapping district’s rate. Everything else about the system — deadlines, appeals, tax sales — flows from that basic structure.

Illinois Taxes Are Paid a Year Behind

The most important feature of the Illinois system is that property taxes are collected in arrears. A bill that arrives in 2026 covers your 2025 tax obligation.¹ That timing shift trips up new owners: you may pay taxes on a house you sold months ago, while the taxes on your new home don’t come due until the following year.

Most counties split the annual bill into two installments, with the first typically due around June 1 and the second around September 1. If bills go out late — after May 1 — the first installment is due 30 days after the date printed on the bill.² Cook County runs on a different schedule, with an accelerated first installment due in the spring based on a percentage of the prior year’s total tax.

Late payments get expensive quickly. Outside Cook County, unpaid taxes accrue interest at 1.5% per month. Cook County reduced its rate to 0.75% per month for tax year 2023 and later.³

How Your Bill Is Calculated

Your final tax bill is the product of a formula with several inputs, each set by a different entity. Understanding what each step contributes is what lets you spot when something is off.

Fair Market Value and Assessment Level

Your county assessor starts by estimating your home’s fair market value using recent sales, property characteristics, and neighborhood conditions. That figure is then reduced to an assessed value.

In 101 of Illinois’s 102 counties, the assessor values residential property at 33.33% of fair market value. A $300,000 home would carry an assessed value of $100,000. Cook County is the exception. Residential property there is assessed at 10% of fair market value, and commercial and industrial property at 25%.⁴ The lower Cook County residential rate was designed to shift more of the burden onto commercial property, though the equalization factor pulls the effective assessment level back toward the statewide standard.

The Equalization Factor

The Illinois Department of Revenue assigns each county an equalization factor, known as the multiplier, to bring the median assessment level in line with the 33.33% target the law requires. When a county’s assessments come in below the target, the multiplier goes above 1.0 and pushes assessed values up. When assessments run high, the multiplier drops below 1.0.⁴

Your assessed value multiplied by the equalization factor produces your Equalized Assessed Value, or EAV. This is the number that drives your bill.

Levies, Rates, and the Final Number

Every taxing district your property sits in — school district, park district, library district, municipality, county, and often several others — sets an annual levy, which is the total amount of money it needs to raise. Each district’s tax rate is its levy divided by the total EAV of all property inside its boundaries.

Your bill equals your property’s EAV (minus any exemptions you qualify for) multiplied by the combined rate of every district that covers you. Property taxes are collected locally and distributed directly to those taxing bodies.⁵ Two identical homes in different neighborhoods can carry very different bills because they fall under different combinations of districts with different rates.

What Causes Your Assessment to Change

Assessors don’t fix your value once and leave it alone. Most Illinois counties use a four-year reassessment cycle. Cook County uses a triennial cycle that rotates through three groups: City of Chicago townships, north suburban townships, and south suburban townships. South suburban townships are scheduled for reassessment in 2026.

Certain changes to the property can trigger an adjustment outside the regular cycle. Adding livable square footage is the most common: a second story, an extra bedroom, or a finished basement. Detached garages, pools, and converting a garage into living space also get flagged, usually because the building permit gets recorded with the county. Routine maintenance and cosmetic updates like paint or carpet generally do not increase your value, but a full kitchen or bathroom remodel with high-end finishes can.

Exemptions That Lower Your Bill

Illinois offers several exemptions that reduce your EAV before the tax rate is applied. They don’t touch the rate itself; they shrink the taxable value. You can often stack more than one if you qualify.

General Homestead Exemption

Any owner-occupied principal residence qualifies. The exemption reduces your EAV by the amount your current-year EAV exceeds the property’s 1977 base-year EAV, capped at $10,000 in Cook County, $8,000 in counties bordering Cook County, and $6,000 in all other counties.⁶ Most long-time homeowners hit the cap because property values have risen well past 1977 levels.

Senior Citizens Homestead Exemption

Homeowners 65 or older (including those turning 65 during the assessment year) get an additional EAV reduction on their primary residence. The maximum is $8,000 in Cook County and contiguous counties, $5,000 elsewhere.⁷ This stacks on top of the General Homestead Exemption.

Senior Citizens Assessment Freeze

A separate program, and often far more valuable where prices are rising fast. Homeowners at least 65 with household income of $75,000 or less for the 2026 tax year can freeze their EAV at the level it was when they first qualified. As long as you continue to meet the income and residency requirements, market appreciation and inflation will not push your EAV up. Rates can still rise, and improvements can still bump the value, but the biggest driver of increases is off the table.⁸

Persons with Disabilities Homestead Exemption

Owners with a disability who occupy their primary residence receive a flat $2,000 annual EAV reduction. The owner must have a legal or equitable interest in the property and be liable for the taxes.⁸

Exemptions for Veterans with Disabilities

Illinois runs two separate programs for veterans with service-connected disabilities. Under the Standard Homestead Exemption for Veterans with Disabilities, a rating of 30–49% brings a $2,500 EAV reduction, 50–69% brings $5,000, and 70% or higher exempts the first $250,000 of EAV entirely. Veterans rated 100% permanently and totally disabled no longer need to reapply annually.⁹ The separate Specially Adapted Housing Exemption allows up to a $100,000 reduction in assessed value for veterans who used federal funds to purchase or build specially adapted housing, and it continues while the veteran, spouse, or unmarried surviving spouse lives in the home.⁸

Senior Citizens Real Estate Tax Deferral

Homeowners 65 or older with household income of $77,000 or less in 2026 can defer all or part of their property tax through a state-run program that functions like a loan against home equity. The state pays the bill, the deferred amount accrues 3% simple interest per year, and a lien secures repayment. The total deferred, including interest and fees, cannot exceed 80% of your equity, and no sale or transfer can close until the deferred amount is paid off.¹⁰ The program fits homeowners who are house-rich and cash-poor and intend to stay put.

Appealing Your Assessment

The numbers on your assessment notice are a starting point. Boards of review reduce assessments regularly when owners bring solid evidence.

Build the Case

Pull your property record card from the assessor’s office or website first. Errors in square footage, room count, lot size, or condition happen more often than people expect, and they’re the easiest arguments to win. Next, find recent sales of comparable homes in your area that sold for less than the value the assessor assigned to yours. Three to five good comparables within about a mile, sold within the past year, make a strong showing. A certified appraisal from a licensed appraiser carries real weight when the assessor’s value is far off; the appraisal should reflect value as of January 1 of the tax year in question.

File with the County Board of Review

You file using Form PTAX-230 (for non-farm property) with your County Board of Review, attaching all written evidence — comparable sales, photographs, appraisal reports — at the time of filing.¹¹ The deadline is typically 30 days after the assessor publishes changes for your township, and late filings will not be heard. The exact date varies by township and county, so confirm it with your county assessment office. The board schedules a hearing, which may be in person, by phone, or virtual depending on the county, and issues a written decision by mail.

Take It to the Property Tax Appeal Board

A loss at the Board of Review isn’t the end. You can appeal to the Illinois Property Tax Appeal Board (PTAB), which conducts an independent state-level review. File on the prescribed PTAB form within 30 days of receiving the Board of Review’s written decision, along with a copy of that decision and your supporting evidence.¹² PTAB hearings are more formal and take longer, but they give owners a meaningful second look.

What Happens If You Don’t Pay

Illinois has a well-defined path for delinquent taxes, and it can end in the loss of your home.

Interest starts running the moment an installment goes unpaid, at 1.5% per month in most counties and 0.75% per month in Cook County for tax year 2023 and later.³ If the bill remains unpaid by the county’s annual tax sale, usually held in the fall, your delinquent taxes are sold to a tax buyer. The buyer pays off your tax debt, a tax lien attaches to your property, and the buyer bids a penalty interest rate — from 0% up to 18% every six months — that gets added to what you’ll owe to reclaim the property.¹³

You then have a redemption period to pay everything off and clear the lien. For residential property with six or fewer units, it’s two and a half years from the sale date. Vacant land, commercial property, and larger residential buildings get one year.¹⁴ The redemption amount includes the original taxes, the buyer’s penalty interest, a $50 fee, and any later-year taxes the buyer has paid on your behalf, which carry an additional 12% annual penalty.¹³

If the redemption period expires without payment, the tax buyer petitions the circuit court for a tax deed. Once the court finds the statutory requirements met, it orders the county clerk to issue a tax deed transferring ownership to the buyer. You lose the home, and it happens entirely outside the traditional foreclosure process. Addressing delinquent taxes early, even through a payment arrangement with the county treasurer, is much cheaper than any part of the recovery process later on.

Selling a Home Under an Arrears System

When you sell, you must file Form PTAX-203, the Illinois Real Estate Transfer Declaration, with the county recorder’s office along with the deed. The form reports the sale price and other transaction details the assessor uses to track market values.¹⁵

Because taxes are billed in arrears, closings include a proration that other states don’t need. The seller typically owes the buyer a credit at closing for the portion of the current year’s taxes that accrued while the seller owned the home, even though the bill for those taxes won’t arrive until next year. The credit is calculated from the most recent known tax bill and adjusted for the number of days the seller occupied the home. Buyers should confirm their escrow accounts are set up to handle both the prorated amount received at closing and the full bill that follows.

1
Cook County Treasurer. Why We Pay Property Taxes In Arrears
2
Illinois Department of Revenue. What Should I Do If I Have Not Received My Property Tax Bill for the Second Installment?
3
Illinois General Assembly. Illinois Code 35 ILCS 200 – Property Tax Code, Section 21-15
4
Illinois.gov. 2025 Cook County Tentative Multiplier Announced
5
Illinois Department of Revenue. What Is Property Tax and How Is It Collected and Distributed?
6
Illinois General Assembly. Illinois Code 35 ILCS 200/15-175
7
Illinois General Assembly. Illinois Code 35 ILCS 200/15-170
8
Illinois Department of Revenue. Property Tax Relief – Homestead Exemptions, PTELL, and Senior Citizens Real Estate Tax Deferral Program
9
Illinois General Assembly. Illinois Code 35 ILCS 200/15-169
10
Illinois Department of Revenue. Senior Citizens Real Estate Tax Deferral Program (PIO-64)
11
Illinois Department of Revenue. Assessment Appeals – Property Tax
12
Property Tax Appeal Board. PTAB – Practice and Procedures
13
DuPage County. Tax Redemption Process
14
Illinois General Assembly. Illinois Code 35 ILCS 200/22-5
15
Illinois Department of Revenue. Instructions for Form PTAX-203, Illinois Real Estate Transfer Declaration