(a) A system retiree with a Tier 3 or Tier 4 membership at retirement shall not be required to contribute to the system unless such retiree had not attained either 10 years of service and/or 10 years of membership at retirement. In such event, the retiree shall contribute at the rate of three percent of wages, but only until the retiree shall have attained 10 years of service credit or, if earlier, 10 years of membership based upon the member's date of membership and service at retirement or, if earlier, until such retiree again retires.

(b) A system retiree with a Tier 5 membership at retirement shall contribute at the rate of 3.5 percent of wages until such retiree again retires.

(c) In the case of a Tier 6 member who retires and rejoins the retirement system, such member’s rate of contribution and employer projection period shall be determined by the date the member last entered the retirement system.