40 ILCS 5/11-168

Whenever any amount is refunded, as provided in Sections 11-164 and 11-165, the amounts to the credit of the employee from contributions by the city, shall be transferred to the prior service annuity reserve. Thereafter any such remaining amounts shall become a credit to the remaining amounts shall become a credit to the city to be used to reduce the amount which the city would otherwise pay during a succeeding year. Any amounts accumulated from contributions by the City for widow's annuity for any male employee who becomes a widower after he attains age 65, who is paid a refund, shall remain in the annuity payment reserve.