Cook County Property Tax Bill Schedule & Delays — When Bills Are Mailed and Due

01 · The basicsHow Cook County bills work

Cook County issues property tax bills in two installments each year:

• First installment — exactly 55% of the prior year's total tax, an estimate that doesn't yet reflect the current year's assessment, exemptions, or rate. It's mailed near the end of the prior year and due early in the year (historically around March 1, though the exact date is set annually).
• Second installment — the balance, calculated once the current year's assessed values, exemptions, and tax rates are finalized across every taxing district. Historically mailed in early July and due August 1 — but in recent years it has frequently been delayed into the fall or winter.

02 · The latestThe most recent dates

For Tax Year 2024 (payable in 2025), the County moved off the usual mid-summer schedule:

The 2024 second installment ran nearly four months late, the result of a large-scale overhaul of the county's property-tax computer systems. Separately, a state law passed in late 2025 pushed the 2025 first installment to April 1, 2026 — about a month later than the traditional March date — to give property owners more breathing room between bills. The 2025 second installment was due October 1, 2026: two months after the statutory August 1 date, and about ten weeks earlier in the year than the 2024 bill. What that bill contains and what paying it late costs: Cook County 2nd installment 2025.

03 · Why lateWhy Cook County bills have run late

The delays aren't random — they're built into a multi-agency process:

• The bill depends on finalized data. The Assessor must complete assessments, the Board of Review must resolve appeals, and the County Clerk must certify rates across hundreds of taxing bodies before the Treasurer can issue a second-installment bill.
• A system modernization slowed the workflow. For 2024, a county technology upgrade caused months-long delays in processing assessments and generating bills; bills can't legally be issued until all the data is certified.
• Reassessment years add volume. Heavy appeal activity in triennial reassessment years can push the second installment later still.

04 · The historyA year-by-year due-date history

The second installment is the one that moves. Here's how the recent schedule has trended:

The statutory due date for the second installment is August 1. Tax Year 2021's December 30, 2022 due date was the latest on record. After a brief return to schedule for Tax Year 2023, the 2024 bill slipped again — so it's wise to budget for a possible late-fall or winter second installment and confirm the current date each year.

05 · How to checkHow to check and pay your bill

Whether or not your paper bill has arrived, you can view and pay online:

• Cook County Treasurer's website — search by PIN or address to see your due dates, view or download your bill, and pay.
• Cook County Property Tax Portal — look up your bill and payment history by PIN or address.
• Keep your mailing address current with the Treasurer's Office so future bills reach you.

06 · AppealsHow delays relate to appeals

Two things are worth separating. First, appeals can affect bill timing: the Assessor and Board of Review must finish assessments and appeals before rates are certified, so heavy appeal volume in reassessment years can push the second installment later. Second — and more useful to you — a late bill doesn't change your right to appeal. You can challenge your assessed value every year, and a successful appeal lowers your assessed value, which lowers the bill whenever it's issued. If your second-installment bill looked higher than expected, that's the moment to check whether your assessment is fair.