A disability retirement benefit is computed under the guaranteed minimum annuity if
it yields a higher benefit than the general formula. The guaranteed minimum is the
lesser of the two following amounts:
forty percent of the employee's high-3 average pay; or
the amount obtained under the general formula after increasing the employee's actual
creditable service by the time between the separation date and the date of attainment
of age 60 (“service to age 60”).
Under the guaranteed minimum formula, an annuity based on 40 percent of the high-3
does not involve OPM's use of pre-1957 MS; thus, SS may grant wage credits. An annuity
based on “service to age 60” will include pre-1957 MS and, as under the general formula, SS wage credits are precluded.