5 C.F.R. § 842.203
General eligibility requirement
An employee must have at least 5 years of civilian service creditable under FERS to be eligible for an annuity under this subpart, except as provided under part 846 of this chapter.
An employee must have at least 5 years of civilian service creditable under FERS to be eligible for an annuity under this subpart, except as provided under part 846 of this chapter.