Illinois Property Tax

Calculating Property Taxes in Illinois

You can calculate Illinois property tax by multiplying a property’s Equalized Assessed Value by the local tax rate, which reflects a county’s funding needs for schools, public safety, infrastructure, libraries, parks, and more.

Property tax calculation:

Property tax = (Equalized Assessed Value − Exemptions) ÷ 100 × tax rate

To start, county assessors determine a property’s fair market value (FMV) and then apply a set assessment percentage (typically 33.33% for most properties outside Cook County). After that, they multiply your property’s fair market value by the assessment percentage to arrive at your equalized assessed value (EAV). From there, they will subtract any exemptions, divide the number by 100, and multiply it by your local tax rate.

In Cook County, property tax regulations are a bit trickier. Classification rules apply different rates to residential, commercial, and industrial properties. Local tax officials reassess on varying schedules, meaning tax bills can be harder to predict.

New and recent laws: In 2024 and 2025, Illinois passed several property tax changes to help homeowners, especially in Cook County. These reforms expanded senior exemptions, reduced interest rates on delinquent taxes, and introduced relief programs for those facing steep tax hikes. Lawmakers also proposed temporary caps on tax revenue growth to slow increases.

National comparison: Illinois property taxes rank among the highest in the U.S. In 2024, the average effective rate was 2.08%, slightly lower than New Jersey’s 2.23% and a tick higher than Connecticut’s 1.96%.

County/Municipality-Specific Rates

In Illinois, property tax rates shift regularly from one county to the next, as local budgets, school funding needs, and changing populations influence them. What you pay reflects the services and infrastructure your community requires in a given year.

Lake County: 3.20% — One of the highest rates in Illinois. Cities like Waukegan, Lake Forest, and Libertyville drive the average up, with well-rated schools and fully built-out city services pushing property taxes higher across the board.

Will County: 2.62% — This growing suburban area runs above the state average. Cities like Joliet, Bolingbrook, and Plainfield anchor the county and carry a solid tax load tied to expanding neighborhoods, schools, and public services.

Kane County: 2.60% — Tax rates in Kane run close to Will County’s. Cities like Aurora, Elgin, and Geneva bring a mix of historic industry and suburban growth, which keeps property taxes in the mid-to-high range for most homeowners.

DuPage County: 2.22% — Just above the state average, DuPage includes cities like Naperville, Wheaton, and Elmhurst. The mix of upscale neighborhoods and busy commercial zones helps explain the higher rate.

Cook County: 2.02% —Cook County’s tax rate is around the state average. While Chicago contributes significantly to the overall figures, suburbs such as Evanston, Oak Park, and Schaumburg also generate tax revenue and influence the county’s rate.

Reassessments and Increases

Reassessment frequency: While most counties in Illinois conduct a complete reassessment every 4 years, Cook County operates on a 3-year cycle. Assessors may also choose to update valuations between these periods if a property undergoes significant changes, like major renovations or an ownership change.

Renovations and improvements: In Illinois, major upgrades (like additions, finished basements, or ADUs) can trigger a reassessment and raise property taxes. If the project requires a permit, the assessor will likely flag a property for review and adjust its value to match the improvements.

Reassessment impact: Big improvements like additions or finished basements often increase property taxes. A reassessment can bump your home’s worth, but the Home Improvement Exemption can shield up to $75,000 of that added value for 4 years.

Reducing Taxes and Exemptions

In Illinois, you’re not necessarily stuck with your property tax bill when it arrives. You can apply for exemptions, check for mistakes, or challenge the valuation through an appeal. If something looks off, take a closer look.

Appeals: If your assessed value looks too high, you can file an appeal with your county assessor or board of review. Most counties give you 30 days to respond to a tax notice, but always double-check the deadline on your notice.

You can also lower your tax bill with exemptions. Illinois offers several options that could apply, depending on your situation. Here are a few worth looking into:

Senior citizen: Homeowners aged 65 or older can get a break on property taxes through the General Homestead Exemption. You might also qualify for extra savings under the Senior Citizens Homestead Exemption if you meet certain income limits.

Disabled veteran: Illinois offers property tax breaks for veterans with a service-connected disability. The more severe the disability, the higher the exemption. 

• 30–49% disability: $2,500 off
• 50–69%: $5,000 off
• 70% or more: First $250,000 exempt

Gold Star spouse: If a service member dies in the line of duty, their surviving spouse may qualify for a full property tax exemption. To retain the tax break, the spouse must stay unmarried and file each year with documents that prove eligibility.

Organization-specific: In Illinois, nonprofits can forego property taxes only if they use the property for education, religion, charity, government work, etc. To qualify, these nonprofits must apply through the County Board of Review.

Property Tax Deductions

Tax deductions: In Illinois, landlords can write off property taxes on rental properties as a business expense. You can also deduct things like insurance, depreciation, and repairs. These expenses help lower your taxable rental income and keep more money in your pocket.

Forms: Landlords should list rental income and expenses on IRS Schedule E (Form 1040). If you run the property more like a business and offer extra services, you may need to file Schedule C instead.

How Often You Pay Taxes

Payment frequency: In Illinois, property owners pay property taxes in two installments yearly. Some counties accept partial payments, but local rules and deadlines vary, so review them closely. Late payments rack up interest, and penalties apply to unpaid balances.

Due dates: Most Illinois counties require property owners to pay the first installment by June 1 and the second by September 1. If the county mails the bill late, they set the first due date 30 days from the mailing date.

Late payments: Counties charge interest when property owners miss a tax deadline. For residential properties, interest compounds at 1.5% per month, whereas nonresidential and multifamily properties face extra penalties after the due date.

How to pay: Property owners pay taxes through their county treasurer’s office. Most counties offer several ways to pay: online, by mail, in person, or by using a secure drop box outside the office. Check local guidelines before submitting a property tax payment.

What do property taxes pay for in Illinois?

Illinois property taxes fund local essentials like schools, police and fire services, road repairs, and community programs. These dollars help keep daily operations running and give counties the resources to serve residents and maintain public infrastructure.

Education: In Illinois, property taxes play a significant role in funding public schools. They help cover teacher pay, staff support, and classroom needs like books and technology upgrades. The amount a district collects can directly affect the quality of education it provides.

Public safety: Property taxes help pay for local police, fire departments, and EMS crews. Counties and cities can add additional taxes if they need more funding.

Infrastructure: Illinois uses property tax dollars to fix roads, keep highways operational, and support public transit like Metra and CTA buses. These funds also help maintain water systems and other core infrastructure that keep towns and cities running smoothly.

Government services: Local governments use property taxes to fund local services like libraries, parks, trash pickup, rec centers, and conservation efforts. In some areas, tax dollars go toward tourism programs that aim to bring visitors to town.

Resources and Contacts

• Illinois Landlord-Tenant Guide
• Illinois Department of Revenue: Property Tax Overview
• Cook County Assessor’s Office
• DuPage County Assessor’s Office
• Lake County Assessor’s Office
• Will County Assessor’s Office
• Kane County Assessor’s Office
• McHenry County Assessor’s Office