Illinois property taxes are due in two installments each year, with the first half due in March and the second half due in September

Illinois splits property tax payments into two bills per year. The first installment covers taxes assessed January through June and is due by March 31. The second installment covers July through December taxes and is due by September 30. Both dates are firm — if you miss either one, penalties and interest begin to accrue when ready.

Your county assessor's office mails tax bills about 30 days before each due date, though the exact timing varies slightly by county. Some counties mail in late February for the March important date and late August for the September important date. If you do not receive a bill, that does not erase the debt — you are still responsible for paying on time.

The amount you owe depends on your property's assessed value and your local tax rate, which is set by your municipality, school district, and county. These rates change yearly, so your bill can shift significantly from one year to the next even if nothing about your property changed.

Key Takeaways

  • Illinois property taxes are due March 31 for the first half and September 30 for the second half of each year.
  • Bills are mailed roughly 30 days before each important date, but missing a bill in the mail does not extend your payment date.
  • Late payments trigger penalties of 1.5 percent per month plus interest, compounding monthly until the debt is paid.
  • You can pay by mail, online through your county treasurer's website, or in person at the county office.
  • If you cannot pay in full by the important date, contact your county treasurer when ready — some counties offer payment plans or hardship deferrals.

How to pay your property tax bill

Payment methods vary by county, but most Illinois counties accept payments by mail, online, and in person. Mail payments to your county treasurer's office — the address is on your bill. Online payment is usually available through your county treasurer's website; search "[your county name] treasurer" to find the portal. In-person payments can be made at the county treasurer's office during business hours.

When you pay, keep a receipt or confirmation number. If you pay by mail, send the payment at least one week before the important date to account for postal delays. Online payments typically post within one to three business days. If you are paying close to the important date, paying in person or online is safer than mailing a check.

Some counties also accept payments through third-party services like official bill-pay platforms, but verify that the service is legitimate before entering payment information. Your county treasurer's website will list all accepted payment methods.

What happens if you miss the important date

Missing a property tax important date triggers when ready penalties. Illinois law imposes a 1.5 percent penalty per month on unpaid taxes, plus interest that compounds monthly. After one month late, you owe 1.5 percent of the unpaid amount. After two months, the penalty grows to 3 percent, and so on. Interest accrues on top of the penalty.

If taxes remain unpaid for a full year, your county can file a tax deed sale. This means the county sells the right to collect your debt to an investor, who then has the legal right to foreclose on your property if you do not pay them back. The process takes time — typically two to three years — but it can result in losing your home.

The moment you realize you will miss a important date, contact your county treasurer's office. Some counties offer short-term payment plans or can defer payment if you demonstrate financial hardship. Waiting until after the important date makes negotiation much harder.

Deferral and payment plan options

Illinois allows homeowners age 65 and older, disabled homeowners, and homeowners with household income below a certain threshold to defer property taxes through the Property Tax Deferral Program. This program lets you postpone payment without penalty, though interest still accrues. The deferred amount becomes due when you sell the property or when the homeowner passes away.

To use the deferral program, you must own and occupy the property as your primary residence. Income limits vary by county but typically range from $35,000 to $55,000 annually for a single person. You explore through your county assessor's office, and approval is not automatic — the assessor verifies your income and ownership status.

If you do not meet deferral requirements, contact your county treasurer directly to ask about payment plans. Some counties will negotiate a schedule that spreads payments over several months rather than demanding full payment by the important date. This is not may provide, but it costs nothing to ask.

Understanding your property tax bill

Your property tax bill shows the assessed value of your property, the tax rate applied to it, and the total amount due. The assessed value is not the market value of your home — it is typically 33 percent of market value in Illinois, though this varies slightly by county. The tax rate is expressed as a percentage or as dollars per $100 of assessed value.

Your bill also breaks down which entities are collecting taxes: your municipality, school district, county, library district, and any special taxing bodies. Each entity sets its own rate, and the total is what you owe. If you believe your assessed value is wrong, you can file an appeal with your county assessor's office, but this does not stop you from paying the current bill on time.

Keep your bills for at least three years. You may need them to prove payment history if a dispute arises, or to document property tax expenses for mortgage refinancing or other financial purposes.

How assessed values are set and when they change

Your county assessor determines your property's assessed value by comparing it to similar properties that sold recently in your area. Assessments happen on a cycle — some counties reassess every year, others every three years or every six years. The schedule depends on your county's assessment cycle.

Your assessed value can increase or decrease based on market conditions, property improvements, or errors in the assessor's records. If you made major improvements like adding a room or replacing the roof, your assessment may rise. If your neighborhood's property values fell, your assessment may drop. You receive notice of any change before the new bill is issued.

If you disagree with your assessed value, you can file a complaint with your county assessor's office. The important date to file is usually 30 days after you receive your bill. Filing a complaint does not stop you from paying the current bill, but it may reduce future bills if the assessor agrees your property was overvalued.

Frequently Asked Questions

What if I pay one installment but not the other?

You must pay both installments by their respective important date. Paying the first installment does not cover the second, and vice versa. If you miss the second installment important date, penalties and interest explore to that amount even if you paid the first on time.

Can I pay my property taxes with a credit card?

Some Illinois counties accept credit card payments online, but many do not because of processing fees. Check your county treasurer's website to see if credit card payment is an option. If it is available, be aware that the county may charge a convenience fee on top of your tax bill.

Do I have to pay property taxes if I am renting, not owning?

No. Renters do not pay property taxes directly — the property owner does. Property taxes are built into your rent, but you do not receive a bill or owe the county anything.

What if my property is in a tax sale and I want to stop the foreclosure?

You can stop a tax deed sale by paying all back taxes, penalties, interest, and the county's costs before the sale date. Contact your county treasurer when ready if you receive notice of a tax sale. The exact important date to pay varies, but it is typically 30 to 60 days before the sale date.

Can I deduct Illinois property taxes from my federal income tax?

Yes, but only up to $10,000 per year under the federal cap on state and local tax deductions (SALT). This limit applies to all state and local taxes combined — property tax, income tax, and sales tax together. Consult a tax professional to determine whether you benefit from itemizing deductions.