Yes. The Cook County Treasurer accepts American Express, Discover, Mastercard and Visa, credit or debit, on cookcountytreasurer.com. A third-party processor charges a 2.08% fee, about $104 on a $5,000 bill. The fee goes to the processor, not the county, and it is not refunded.
The free way to pay online is from a checking or savings account (ACH) on the same site. Chase branches in Illinois, more than 100 community banks (for their own customers), the mail and the Treasurer's office at 118 N. Clark Street, Room 112, are free as well.
Start from cookcountytreasurer.com itself: the Treasurer says its site is the only online payment system it authorizes. Owners paying ten or more PINs online owe a $2.00 processing fee per PIN, per installment.
The Tax Year 2025 second installment was due Thursday, October 1, 2026; an unpaid balance now accrues interest of 0.75% a month. For every way to pay and what happens if you pay late, see how to pay Cook County property taxes.