Mississippi Code Title 33. Military Affairs § 33-13-355

(1) Any period of confinement included in a sentence of a court-martial begins to run from the date the sentence is adjudged by the court-martial but periods during which the sentence to confinement is suspended or deferred shall be excluded in computing the service of the term of confinement.

(2) On application by an accused who is under sentence to confinement that has not been ordered executed, the convening authority or, if the accused is no longer under his jurisdiction, the officer exercising general court-martial jurisdiction over the command to which the accused is currently assigned, may in his sole discretion defer service of the sentence to confinement. The deferment shall terminate when the sentence is ordered executed. The deferment may be rescinded at any time by the officer who granted it or, if the accused is no longer under his jurisdiction, by the officer exercising general court-martial jurisdiction over the command to which the accused is currently assigned.

(3) In the militia or state military forces not in federal service, no sentence of dismissal or dishonorable discharge may be executed until all reviews and any appeals to the Mississippi Court of Military Appeals are complete.

(4) All other sentences of courts-martial are effective on the date ordered executed.