65 ILCS 5/10-4-3
The corporate authorities of any municipality may withhold and deduct from the compensation of each of its employees who consents thereto, a specified amount each pay period for the purchase of United States Savings Bonds for the benefit of such employee and in such denomination as may be stated. The account of each employee shall be kept separate. As often as the individual account of any such employee contains a credit sufficient to purchase a bond of the denomination stated, the withholding officer shall arrange for or make such purchase as directed by such employee, and shall deliver such bond to such employee.
Whenever any employee is separated from municipal service, any sum to his credit in such withheld compensation funds shall be paid to him or to his estate on request.
65 ILCS 5/10-4-3