In the preceding question, you refer to a length of separation (break in service). What is the length of separation that determines if an individual retains CSRS or CSRS Offset coverage?
Generally, CSRS Offset retirement coverage occurs when an employee who had previously been covered under CSRS has a break in service of over 365 days. When the individual returns to a permanent position they will be covered under CSRS Offset and will contribute to both CSRS and to FICA (Social Security). In other words, CSRS Offset coverage applies to individuals who are simultaneously covered by CSRS and by Social Security.