Even after spending time in the military, some may choose to take a break from it for a while after their contract is up, or even transfer to a different branch. Despite having the experience of already going through military training, sometimes it may be harder to re-enlist after time off.
One reason it may be harder is because a soldier that has prior enlistment can come back in with similar pay as when he left, making it a different level of enlistment than other new recruits.

What is Prior Service?
Depending on the different branches, the requirements may differ. The Air Force defines “prior service” as anyone who has served 24 months or more as an active duty soldier. Anyone who has served less than those 24 months are classified as “previous service” and can undergo a separate enlistment procedure. The Air Force has the right to accept or turn away any applicants, and it often depends on the needs of the branch.

How many can re-enlist?
Each branch can limit the amount of soldiers they accept as prior-service each year. It may be tricky to get in, because the military will sooner allow someone currently enlisted to re-enlist before they accept a prior-service that can take up additional space in their quota.

How hard is it to get in to the Air Force with prior service?
While each branch may be hard to get into, the Air Force can be selective when choosing prior-service enlistments. Having skilled qualifications within a specialized field may increase the chances of being accepted.

Can I choose a new job?
Most of the time, the candidate must enlist in the job they had when the contract ended, unless that job has been modified or moved. Despite what branch of the military a soldier was involved in, chances are they would put them in the field that best represented their skills and knowledge.
Do I need to complete basic training again?
Each service varies on this, but the Air Force may send all accepted prior service to an Air Force familiarization course.