40 ILCS 5/15-113.11: Service for periods of voluntary or involuntary furlough.

(a) A participant may establish creditable service and earnings credit for periods of furlough beginning on or after July 1, 2009 and ending on or before June 30, 2011. To receive this credit, the participant must (i) apply in writing to the System before December 31, 2011; (ii) not receive compensation from an employer for any furlough period; and (iii) make, on an after-tax basis, employee contributions required under Section 15-157 based on the rate of basic compensation during the periods of furlough, plus an amount determined by the Board to be equal to the employer's normal cost of the benefit, plus compounded interest at the actuarially assumed rate from the date of voluntary or involuntary furlough to the date of payment. The participant shall provide, at the time of application, written certification from the employer providing the total number of furlough days a participant has been required to take.

(b) A participant may establish creditable service and earnings credit for periods of furlough beginning on or after July 1, 2015 and ending on or before June 30, 2017. To receive this credit, the participant must (i) apply in writing to the System before December 31, 2018; (ii) not receive compensation from an employer for any furlough period; and (iii) make, on an after-tax basis, employee contributions required under Section 15-157 based on the rate of basic compensation during the periods of furlough, plus an amount determined by the Board to be equal to the employer's normal cost of the benefit, plus compounded interest at the actuarially assumed rate from the date of voluntary or involuntary furlough to the date of payment. The participant shall provide, at the time of application, written certification from the employer providing the total number of furlough days a participant has been required to take.