5 ILCS 340/4
An employee may authorize the withholding of a portion of his or her salary or wages for contribution to a maximum number of 4 organizations described in paragraphs (b) and (c) of Section 3 of this Act. A department, board, body, agency or commission may direct the State Comptroller to deduct, and the University of Illinois, Southern Illinois University, Chicago State University, Eastern Illinois University, Governors State University, Illinois State University, Northeastern Illinois University, Northern Illinois University, and Western Illinois University may deduct, upon written request of a State employee, for each regular payroll period, from the salary or wages of the employee the amount specified in the written request for payment to the organization designated by the employee. The moneys so deducted shall be paid over promptly to the organizations designated by the employee by means of warrants drawn by the State Comptroller, the University of Illinois, Southern Illinois University, Chicago State University, Eastern Illinois University, Governors State University, Illinois State University, Northeastern Illinois University, Northern Illinois University, and Western Illinois University, against the appropriation for personal services of the department, board, body, agency or commission by which such employee is employed.
Such deductions may be made notwithstanding that the compensation paid in cash to such employee is thereby reduced below the minimum prescribed by law. Payment to such employee of compensation less such deduction shall constitute a full and complete discharge and acquittance of all claims and demands whatsoever for the services rendered by such employee during the period covered by such payment.
Such request for deduction may be withdrawn at any time by filing a written notification of withdrawal with the department, board, body, agency or commission, the University of Illinois, Southern Illinois University, Chicago State University, Eastern Illinois University, Governors State University, Illinois State University, Northeastern Illinois University, Northern Illinois University, or Western Illinois University, by which such employee is employed.
5 ILCS 340/4