5 C.F.R. § 340.403 : Administrative Personnel — OFFICE OF PERSONNEL MANAGEMENT — CIVIL SERVICE REGULATIONS — OTHER THAN FULL-TIME CAREER EMPLOYMENT (PART-TIME, SEASONAL, ON-CALL, AND INTERMITTENT) — SEASONAL AND INTERMITTENT EMPLOYMENT — Intermittent employment

(a) Appropriate use. An intermittent work schedule is appropriate only when the nature of the work is sporadic and unpredictable so that a tour of duty cannot be regularly scheduled in advance. When an agency is able to schedule work in advance on a regular basis, it has an obligation to document the change in work schedule from intermittent to part-time or full-time to ensure proper service credit.
(b) Noncompetitive movement. Intermittent employees serving under career appointment may move to other positions in the same way as other regular career employees.

5 C.F.R. § 340.403