September 19, 2018 20:15 Updated Follow There are several things that factor into the final cost of extra service. We suggest you read Buying Extra Service Credit if you are a member of PERF or TRF. For other funds, . Related articles What is service credit? How can buying extra service credit give me a higher monthly pension benefit? How much will my 13th check be? How do I sign up for a Lunch and Learn? How do I get copies of my records?