Rules governing the tour length required in a Joint Duty Assignment List (JDAL) billet, and the appropriate joint tour credit, are dictated by Title 10, Section 664. All orders to an initial JDAL tour are written for 36 months. Tour lengths may be shortened for Critical Occupational Specialty (COS) officers. These officers are from the Aviation, SWO, SUB, EOD and SEAL communities, and they may be transferred, under a special Title 10 provision, after 22 month day-for-day service in their first JDAL billet. TRANSFERRING SO MUCH AS 24 HOURS EARLY CAN RESULT IN NO JOINT CREDIT!! If you fall into this category be sure to check with your detailer to confirm your check in (diary) date and that it's going to be possible for you to leave your billet.
Officers who do not fall under the COS provision are required to serve a minimum of 34 months day for day. If there is a need for you to leave early, your detailer can help you with it. Leaving before the 34 months requires an OSD approved Joint Tour Length Waiver (JTLW); however, there are no guarantees regarding the joint credit you’ll receive with a waiver.
Subsequent JDAL tours (2nd, 3rd, etc.) require a minimum of 24 months day-for-day in the billet.