What are the deferred retirement rules for FERS?
If you leave federal service before being eligible for retirement and leave the money you contributed toward FERS in the retirement fund, you will be eligible for an annuity that starts at age 62 if you had at least five years of creditable civilian service, at age 60 with at least 20 years of service, at the minimum retirement age with 30 years of service, or at the MRA with at least 10 but fewer than 30 years of service (but with the annuity reduced by 5 percent for each year of age, 5/12 percent per month, that you are under age 62 when you begin the benefit). Unused sick leave is not credited in the calculation of a deferred benefit.

The value of this benefit is set according to your high-3 salary and creditable service when you left; it is not adjusted for inflation, overall salary growth or any other factor.