Q. If an employee began work in January 1979 and continued until December 1984, then elected FERS coverage and continued uninterrupted until December 2006, would the offset service period be six years or 27? A. You don’t have offset service. Instead, when you retire, you’ll receive a FERS annuity with a CSRS component. The CSRS component will be based on your six years of CSRS-covered service before you transferred to FERS, and computed using the standard CSRS formula. Your years of FERS service will be computed using the standard FERS formula.