Two installments; dates shift every year, always confirm on the Treasurer's site. If a due date lands on a weekend or public holiday, most counties move it to the next business day — check the county's own notice before relying on the shift.
By post: mail a cheque to the treasurer's office; the postmark date usually counts, not the arrival date.
In person: the treasurer's office during business hours; bring your bill or parcel number.
Mortgage escrow: if your taxes are escrowed, the servicer pays — you still owe the difference if your escrow is short.
Common questions
When are property taxes due in Cook County, IL?
1st installment (tax year 2025): April 1, 2026. 2nd installment (tax year 2025): October 1, 2026.
What happens if I pay late in Cook County?
Penalty after each installment date.
How do I pay Cook County property tax?
Pay online through www.cookcountytreasurer.com, the county's own payment portal, or by post or in person at the treasurer's office.
Is the Cook County deadline the same every year?
Two installments; dates shift every year, always confirm on the Treasurer's site. Counties shift dates when billing is delayed, so confirm against the county source linked on this page.
What if I can't pay in full?
Most counties offer instalment plans or partial payment — ask the treasurer before the due date, not after. Once the bill is delinquent the options shrink and the fees start.
Does a late payment affect my mortgage?
Unpaid property tax is a lien on the property in most states, which your servicer may pay and then bill you for, with fees. It does not disappear.
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StacyApproved is an independent reference and is not a government agency. Deadlines change and exceptions apply — always confirm with your county treasurer using the official link on this page. Nothing here is tax, legal or financial advice.