740 ILCS 170/4
The maximum wages, salary, commissions, and bonuses that may be collected by an assignee for any work week shall not exceed the lesser of (1) 15% of such gross amount paid for that week or (2) the amount by which disposable earnings for a week exceed 45 times the Federal Minimum Hourly Wage prescribed by Section 206(a)(1) of Title 29, U.S.C., as amended, or the minimum hourly wage prescribed by Section 4 of the Minimum Wage Law, whichever is greater, in effect at the time the amounts are payable. This provision (and no other) applies irrespective of the place where the compensation was earned or payable and the State where the employee resides. No amounts required by law to be withheld may be taken from the amount collected by the creditor. The term "disposable earnings" means that part of the earnings of any individual remaining after the deduction from those earnings of any amounts required by law to be withheld. If there is more than one assignment demand received by the employer, the assignees shall collect in the order or priority of service of the demand upon the employer, but the total of all collections shall not exceed the amount that could have been collected if there had been one assignment demand.
Benefits and refunds payable by pension or retirement funds or systems, any assets of employees held by those funds or systems, and any moneys an employee is required to contribute to those funds or systems are exempt and are not subject to a wage assignment under this Act.
A fee of $12 for each wage assignment shall be collected by and paid to the employer and the amount so paid shall be credited against the amount of the wage-earner's outstanding debt.
740 ILCS 170/4