38 CFR § 21.350 - Unauthorized absences.
A veteran who is unable to obtain an authorized leave of absence in advance may seek to have the unauthorized absence excused.
(a) Excusing unauthorized absences. VA may excuse an unauthorized absence and make proper charges against the veteran's leave when:
(1) The veteran has absented himself or herself when advance approval from VA is impracticable; and
(2) Conditions for approval of leave are otherwise met.
(b) Unexcused, unauthorized absences. When an unauthorized absence is not satisfactorily explained, VA will take necessary action, including recoupment of subsistence allowance for that period of absence.