One method of changing Army MOS, or Military Occupational Specialty, while still in active service is to scan periodically posted in and out calls for positions in understaffed MOSs and submit the necessary paperwork to apply for one of these jobs. Another method is to wait until re-enlistment and apply for a position in an understaffed MOS.
The Army offers a wide range of occupational specialties, and it is to a recruit's advantage to peruse these carefully before choosing a particular career path during the enlistment process. It is also worthwhile to take time to study before attempting the Armed Services Vocational Aptitude Battery, or ASVAB, as the final ASVAB score impacts the MOSs for which a recruit qualifies.
Once a soldier is on active duty, staffing needs usually determine the possibility of switching from one MOS to another. Because of the investment in training time, once a soldier has selected and been trained for a particular MOS, he is expected to remain in that job for his entire military career. However, exceptions are made if the MOS the soldier is currently in is balanced or overstaffed and the MOS to which the soldier requests a transfer is understaffed. If soldiers are close to re-enlistment time, they must wait until re-enlistment before requesting reclassification. Another possibility is mandatory reclassification. If a soldier is not working out in his current position or the Army sees a greater need for his skills elsewhere, the Army may move him from one MOS to another.