48 CFR §237.106

(1) Personal service contracts for expert or consultant services shall not exceed 1 year. The nature of the duties must be— (i) Temporary (not more than 1 year); or (ii) Intermittent (not cumulatively more than 130 days in 1 year).

(2) The contracting officer may enter into a contract, exercise an option, or place an order under a contract for severable services for a period that begins in one fiscal year and ends in the next fiscal year if the period of the contract awarded, option exercised, or order placed does not exceed 1 year (10 U.S.C. 3133).