Sec. 13. (a) A member of a retirement system who meets an applicable length-of-service requirement for service retirement benefits but does not meet the applicable age requirement for service retirement benefits may terminate employment with or otherwise discontinue service for the fire department and remain eligible to receive service retirement benefits from the retirement system on attaining the applicable age, as long as the member does not withdraw contributions in the retirement system.

(b) A member who terminates employment or otherwise discontinues service after meeting an applicable length-of-service requirement for service retirement may not be required to pay to the retirement system contributions that become due after the date of termination or discontinuance.