February 25, 2021 15:41 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 Do you accept credit cards? I was a substitute teacher. How can I add this service to my account? Are credit cards and prepaid debit cards for gas given out to participants in court programs allowed? What is needed for payment of credit card charges? How many years of creditable service must I have in order for my spouse or child to receive a survivor benefit from PERF?