In the AF we have AFI 36-2619:
8.4. Man-day tours longer than 30 consecutive days will accrue leave of 2.5 days per month. Compute tour lengths by rounding off to the nearest whole number for tours that do not end exactly on a number divisible into whole months. Tours should not be approved for less than three days when travel is outside the commuting distance of the ARC member.
8.5. Accrued leaves must be taken during the man-day tour and are included in the tour length. ARC members may request leave from their active duty supervisor through their assigned payroll office.
8.5.1. If unusual circumstances preclude taking accrued leave, the ARC member is entitled to be paid for the leave up to a career maximum of 60 days.
I am on orders right now and have taken leave with no problem.