The second installment of property taxes for Cook County was traditionally due on August 1. However, for 2025, there is a significant delay in mailing and due dates of the second installment tax bills. The bills will be mailed at least one month late, making the due date no earlier than September 1, 2025, and possibly later due to the transition to a new tax billing system. Past delays in previous years have also pushed due dates into the fall, with some years seeing due dates as late as December. This delay is attributed to technological issues in the Cook County Assessor’s Office and the final phasing out of an old mainframe system used for tax bill processing.
To summarize:
- Usual due date: August 1
- 2025 expected due date: No earlier than September 1, possibly later, due to system and processing delays
- Delay caused by transition to a new property tax billing system and associated technological challenges
For the most current exact due date, property owners are advised to monitor official Cook County Treasurer updates as the date has not been firmly determined yet.
