55 ILCS 5/3-11018

No bank, savings and loan association, savings bank, or credit union holding county moneys deposited therewith by the county treasurer in accordance with the provisions in this Division, or otherwise, and no officer of any such bank, savings and loan association, savings bank, or credit union, or other person, shall pay to, withhold for the benefit of, or contract in any manner for the payment to such county treasurer, or to any other person for him, of any interest or other fee, perquisite or emolument, on account of the deposit of such county moneys, except such interest as shall be paid to such county treasurer for the benefit of the county.