10 U.S.C. § 12771

(a) Grade on Transfer .— Unless entitled to a higher grade under another provision of law, a reserve commissioned officer, other than a commissioned warrant officer, who is transferred to the Retired Reserve is entitled to be placed on the retired list established by section 12774(a) of this title in the highest grade in which he served satisfactorily, as determined by the Secretary concerned and in accordance with section 1370a of this title , in the armed force in which he is serving on the date of transfer. (b) Effect of Subsequent Recall to Active Status .— (1) If a member of the Retired Reserve who is a commissioned officer is recalled to an active status in the Selected Reserve of the Ready Reserve under section 10145(d) of this title and completes not less than two years of service in such active status, the member is entitled to an adjustment in the retired grade of the member in the manner provided in section 1370a of this title . (2) The Secretary concerned may reduce the two-year service requirement specified in paragraph (1) in the case of a member who— (A) is recalled to serve in a position of adjutant general required under section 314 of title 32 or in a position of assistant adjutant general subordinate to such a position of adjutant general; (B) completes at least one year of service in such position; and (C) fails to complete the minimum two years of service solely because the appointment of the member to such position is terminated or vacated as described in section 324(b) of title 32 .