10 U.S.C. § 14706 — Computation of total years of service

(a) A reserve officer's years of service, for purposes of this chapter and chapter 1407 of this title, include all of the officer's service as a commissioned officer of a uniformed service, except for three things: (1) service as a warrant officer; (2) constructive service; and (3) service after becoming a commissioned officer of a reserve component while in an advanced-education program to earn the first professional degree needed for a professional specialty -- but only the part of that service that happens before the officer starts initial active duty or initial Ready Reserve service in the specialty the degree leads to. (b) The exclusion in (a)(3) does not apply to an officer who already served on active duty, or served as a member of the Ready Reserve outside student status, for the period before their time as a student. (c) For purposes of (a)(3), an officer is considered to be in a professional specialty if they are appointed or assigned to the Medical Corps, the Dental Corps, the Veterinary Corps, the Medical Service Corps, the Nurse Corps, or the Army Medical Specialists Corps, or are designated as a chaplain or judge advocate.