c. The first day of the month following the date the member completes 30 years of creditable service and attains age 57, which service may include a maximum of 4 years of military service credit if such credit is not claimed under any other system and the remaining years are in the Special Risk Class.
For pension plan members, normal retirement age is attained on the normal retirement date. For investment plan members, normal retirement age is the date a member attains his or her normal retirement date as provided in this section, or the date a member is vested under the investment plan as provided in s. 121.4501(6), whichever is later.