A court-martial sentence described in paragraph (2) shall result in the forfeiture of pay, or of pay and allowances, due that member during any period of confinement or parole. The forfeiture pursuant to this section shall take effect on the date determined under
section 857 of this title (article 57) and may be deferred as provided in that section. The pay and allowances forfeited, in the case of a general court-martial, shall be all pay and allowances due that member during such period and, in the case of a special court-martial, shall be two-thirds of all pay due that member during such period.