Cook County Property Tax Bills Delayed

Normally, these bills are mailed in early July and due August 1. This year (2026), Cook County officials say property owners will have at least until October to make their second-installment payment for 2025. (Because Illinois property taxes are paid in arrears, 2025 taxes are paid in 2026.)

The delay stems from ongoing problems with the county's new property tax system, which has pushed back the preparation and mailing of the bills. While the County Board has confirmed that payments won't be due before October, it has not yet announced an exact mailing date or payment deadline.

Buying or selling real estate while tax bills are delayed? You might pay more attention to property tax prorations. When the current bill isn't available, buyers and sellers typically rely on estimated prorations, making it even more important to understand how those numbers are calculated before closing.