US Code
CHAPTER 879— SHIPS’ STORES AND COMMISSARY STORES
§ 8805. Acceptance of Government checks outside the United States

(1) accept any Government check tendered by a retired member of the Navy or the Marine Corps, a member of the Navy Reserve or the Marine Corps Reserve, or a member of the Fleet Reserve or the Fleet Marine Corps Reserve, if the member is the payee of the check and the check is tendered in payment of amounts due from the member to the store; and
(2) refund in cash any difference between the amount due and the amount of the tendered check.