First duty station selection is made (in either basic training or technical school/AIT/A-School), based upon your preferences, and the needs of the service. While the services will consider your preferences, the overriding deciding factor is where the military needs you the most.
Some Navy jobs allow your assignment to be based on your class-standing in "A-School." And of course, it goes without saying that assignments are based on valid vacancies. If you have the job of tank-fixer, you're only going to be assigned to bases that have tanks to fix.
After the first duty assignment, subsequent assignments are done a little differently. In most cases, you'll have a little more say in future assignments, than you have for the first duty assignment. There are a few restrictions, however.
First-term (those in their first enlistment) enlisted members assigned to a continental (CONUS) U.S. location must have 12 months time-on-station before being eligible to move to an overseas location and must have 24 months time-on-station before being allowed to move to another continental U.S. location.
Career (those who have re-enlisted at least once) enlisted members assigned to the continental U.S. must have 24 months time-on-station to move to an overseas location and must have 36 months time-on-station in order to move to another continental U.S. location.
The length of time one spends on an overseas tour depends on the location. For example, most of Europe and Japan are considered standard overseas tours. The length of the assignment is 24 months for single people, or those with dependents who elect not to bring their dependents, and 36 months for those who bring their dependents.
Another type of overseas assignment, like most assignments to Korea, is considered remote. On a remote tour one cannot bring their family at government expense, and the tour-length is 12 months. On the other hand, those returning from a remote tour usually get assignment preference over those returning from a standard tour.
For standard overseas tours, one can generally increase his or her chances of being selected by volunteering for the extended tour length. This is the standard tour, plus 12 months.
Of course, one can be involuntarily assigned overseas as well. In general, this is done based on the military member's last overseas return date.
A follow-on assignment is an assignment after a remote tour. Those with orders for a remote tour can apply for their next assignment before they even depart to the remote tour.
When is assigned to a 12-month remote tour, military members can move their dependents anywhere they want to live in the United States, at government expense, while the member is away. The government must then pay again to relocate the dependents from where they are living to the new assignment when the member returns from the remote tour. Single people, even though they don't have dependents can use the follow-on program, as well.
It's important not to confuse assignments with deployments, which are of course based on many factors such as geopolitical situations and the need for U.S. military troops around the world.
Each of the services also has procedures for hardship assignments. This allows a military member to apply for reassignment to a specific area/base, due to a valid family hardship. The military's definition of hardship is when there are extreme family problems such as illness, death, or extremely unusual circumstances that are temporary in nature and the specific circumstances necessitate the military member's presence.
If the problem is not one that can be resolved within one year, a hardship discharge will be considered, rather than a hardship assignment.
Joint Spouse Assignments
When one military member is married to another military member, both must apply to be assigned together. This is called a joint spouse assignment. The military will try to assign spouses together, but there are no guarantees. The success rate for joint spouse assignments is about 85 percent.
Joint spouse assignments are obviously much easier to accommodate if both spouses are in the same branch of the military.
A permissive reassignment is one that doesn't cost the government any money. Most permissive reassignments are in the form of swaps, which is when one military member finds another with the same rank and job, currently assigned (or with orders) to a base they want to go to.
Both members who agree to swap must pay for their own move. This includes shipment of personal property. Usually, military personnel offices maintain lists of military people worldwide who are looking to swap. In order to be eligible for a swap, one must have the required time-on-station mentioned above. In other words, a first-termer must have 24 months time-on-station to swap with someone at another continental U.S. location.
Base of Preference
Before a military member re-enlists, he can apply to move to a base of his choice. The military, of course, wants this person to re-enlist, so they try to accommodate such base of preference requests. If approved, the member must then re-enlist to accept the assignment.
When you graduate technical school, the military will pay the authorized costs for you to go to your next duty assignment or, to the port of your military flight for overseas assignments.
The military does not pay you for travel on leave. They pay you for direct travel from your old duty assignment to your next duty assignment. If you travel home on leave, any additional cost is out of your pocket.
Privately Owned Vehicle Shipment
If you own a vehicle and get an overseas assignment, the military will either ship the vehicle for you or store it while you are away.
Some locations don't allow the shipping of a personal vehicle and others restrict this privilege to certain ranks. In these cases, the military will store the vehicle for you for free while you are assigned overseas.
The military will pay to move your personal property from your home location to your first permanent duty station, or, you can rent a truck, move it yourself. In such cases, the military will reimburse you a portion of what it would have paid a contractor to move the vehicle.