Cook County Property Tax Bills Will Be At Least One Month Late: Lemont Township Assessor

LEMONT, IL — Second installment property tax bills from Cook County will be mailed at least one month late, according to the Lemont Township Assessor's Office.

Usually tax bills hit mailboxes in late June, and are due around Aug. 1, the Township Assessor's Office said. However, mailing and due dates will be delayed by at least one month due to a switch in the computer system by county agencies.

So, residents can expect tax bills to be due no earlier than Sept. 1, and it could still be later.

"For decades, the county agencies involved in preparing property tax bills have been using a 1980s-era mainframe computer system," the Township Assessor's Office said. "The county has been phasing out the old mainframe for the last few years, but 2025 marks the first year in which the old system will be phased out completely."