What it is
SDAP is extra monthly pay for enlisted members in designated special duty assignments that demand extra responsibility or unusual skills: recruiters, drill instructors, special operations support, and similar billets. It is paid in levels, SD-1 through SD-6.
2026 rate
$75 to $450 per month depending on the SD level of your billet.
What goes wrong
SDAP is tied to the billet, not to you. When you leave the assignment it should stop, and when you arrive it should start. Both transitions generate errors. If your SD level changed, the amount should change the same month.