40 ILCS 5/12-142

Only employees in active status are entitled to ordinary disability. In order that payments may begin from the date of absence, without pay, on account of disability, an employee must file an application within 60 days from the date when the employee was in salary status. If the filing of the application is delayed beyond such period, the benefit shall begin to accrue as of a date not more than 60 days prior to the date on which the application is received by the board.