Illinois Property Tax Due Dates 2026: When Bills Are Due

Illinois property tax due dates decide when you pay and when penalties start, so they are worth knowing cold. Miss one and interest and late fees pile up fast. This guide lays out the Illinois property tax due dates, when bills are mailed, and what to do if the bill looks wrong. If you pay through a mortgage escrow account, your lender usually handles the dates, but it is still

your job to make sure the bill is correct.

Illinois Property Tax Due Dates: When to Pay

Here are the Illinois property tax due dates. Two installments, with dates set by county. Cook County is typically about March 1 (first) and August 1 (second); many downstate counties use a June and September schedule. Taxes are paid one year in arrears. Confirm with your county treasurer.

Late taxes accrue 1.5% per month (18%/year); many homeowners pay through a mortgage escrow account.

When Illinois Property Tax Bills Are Mailed

Bills are mailed by the county treasurer/collector before each installment. If a bill does not arrive, do not assume you owe nothing — not getting a bill usually does not excuse a late payment. Contact your treasurer if you think a bill is missing, and keep your mailing address current with them. The mailing is your signal that the Illinois property tax due dates are close.

Paying Illinois Property Tax: Escrow vs. Paying Yourself

There are two common ways homeowners pay property tax. If you have a mortgage, your lender often collects a slice of the tax with each monthly payment, holds it in an escrow account, and pays the county for you when the bill comes due. That is convenient, but it is still worth checking your annual escrow statement — if your assessment jumps, your monthly payment can rise, and an error

in the assessment quietly costs you every month.

If you own your home outright or your loan does not escrow, you pay the county directly on the schedule above, so those Illinois property tax due dates are yours to track.

Either way, the responsibility to make sure the bill is correct is yours. Escrow only pays the number on the bill — it does not check whether that number is fair. That is why reviewing your assessment each year matters even when a lender handles the payment.

What If You Can’t Pay Your Illinois Property Tax on Time?

If money is tight, the worst move is to go silent. Unpaid property taxes add penalties and interest, and over time an unpaid balance can become a lien on your home and, eventually, a tax sale. The good news is that help usually exists if you ask early. Contact your county treasurer or tax collector before the Illinois property tax due dates hit and ask what is available — many

offer payment plans that spread the balance over several months.

Older homeowners and those on a fixed income should also look at the relief programs on our exemptions page — a homestead, senior, veteran, or disability break can shrink the bill, and some states let qualifying seniors defer payment until the home is sold. Acting early keeps you in control and out of the penalty spiral.

If Your Illinois Bill Looks Wrong

Paying on time and challenging an unfair value are two different things — and you should do both. Pay the bill as billed to avoid penalties, and separately, if the assessed value behind the bill is higher than what your home would sell for, you can appeal it. In Illinois, appeals are heard by County Board of Review (then the Illinois Property Tax Appeal Board / PTAB). Note the deadline:

File a complaint with your County Board of Review within 30 days after your township’s assessment list is published (the date varies by township/county; in Cook County the window opens township by township).

If denied, appeal to the Illinois Property Tax Appeal Board (PTAB) within 30 days. Confirm your township’s exact deadline with the assessor. Fixing an over-assessment is the most reliable way to bring the bill itself down for years to come.

Don’t want to appeal your Illinois taxes yourself? A property tax appeal service can file everything for you and usually only charges if it wins — typically a share of what it saves you. It is one option; you can also appeal on your own for free.

Frequently Asked Questions

What are the Illinois property tax due dates?

Two installments, with dates set by county. Cook County is typically about March 1 (first) and August 1 (second); many downstate counties use a June and September schedule. Taxes are paid one year in arrears. Confirm with your county treasurer. Confirm your exact dates with your county treasurer.

When are Illinois property tax bills mailed?

Bills are mailed by the county treasurer/collector before each installment.

What happens if I miss the Illinois property tax due dates?

Late property taxes add penalties and interest, and long-term nonpayment can put a lien on the home. If a bill is unaffordable, contact your treasurer early — many offer payment plans.

My Illinois bill seems too high — what can I do?

Pay it on time to avoid penalties, then appeal the assessed value with County Board of Review (then the Illinois Property Tax Appeal Board / PTAB) if your home is valued above market. Correcting the value lowers future bills.

Illinois Property Tax Sources & Data

• Tax Foundation — Property Taxes by State & County: taxfoundation.org
• U.S. Census Bureau (American Community Survey): census.gov/acs
• Lincoln Institute of Land Policy (property tax data): lincolninst.edu

Due-date and billing details for Illinois on this page were verified from official Illinois state and county sources
and last checked in July 2026. Payment dates are set locally and change — confirm your exact due dates with your county
treasurer or tax collector before you rely on them.

More Property Tax Guides

• Property Tax Rates by State
• Property Tax by County
• Are You Overpaying? Over-Assessment Checker
• Property Tax Exemption Finder

Disclaimer: This guide is informational only and is not legal, tax, or financial advice. Know Property Tax is an independent educational resource. It is not a government agency, not a county assessor, and not a tax-appeal service. Property tax rates, bills, exemptions, and deadlines change over time and vary by county and property. Confirm anything that affects your taxes with your county assessor or a licensed professional before you act.