Creditable service is the number of years and months of PERS-covered employment PERS uses to calculate your retirement benefits. You earn one month of creditable service for each month you are an active member Tier One/Tier Two member: A member who is presently employed by a participating employer in a PERS Chapter 238 Program qualifying position and who has completed the six-month waiting period. OPSRP member: A member who is presently employed by a participating employer in an Oregon Public Employees Retirement Plan (OPSRP) Program qualifying position and who has completed the six-month waiting period. employed in a qualifying position A qualifying position is one in which an employee will perform 600 or more hours of service in a calendar year in one or more jobs with one or more participating public employers. or concurrent positions and you perform services during what is deemed to be a major fraction Average of 50 hours a month in a calendar year. of a month.