Hello Thomas,
NO RULE on this.
A single, unmarried soldier and all in the military's services are expected to reside in the barracks (or call them doms if you like). The government builds these buildings to house its single military members.
Now, in the old days there were dedicated Bachelor NCO buildings. But, today, most NCOs are married or they are authorized to live off base (Stateside). It makes little sense for the military to invest about $5 million dollars a building to build a bachelor NCO building that can not be filled up.
Now, the single soldier: When your barracks fills up to about 95% occupancy it is usual practice for the Command to authorize barracks residents too begin to move off base so that we have open rooms for new junior lower ranking persons who are coming to the base.
The usual procedure is to go to the most senior E-4 and ask them to move off base and collect BAH and BAS. If that most eligible person declines and wishes to stay in the barracks then we go down the rank list until we do find someone who will move off base and open up bed spaces for new comers.
Example: If we have a barracks with 100 rooms then we have to have at least 5 open rooms. So, if we only have 3 or 4 open rooms we can ask 1 or 2 people to move off base.
So, do not even begin to think that you will move off base right away. And, of course, if you have an assignment pending you won't want to move off base anyway and have the problem of getting furniture and whatever. Single people should not accumulate: STUFF to carry from base to base.
Wait until you get married.
Single soldiers should not even want to remain in the US after their AIT (technical school). Volunteer for Germany, Europe, Asia if you can get it.
Then, when you come back to the USA for your next assignment you will probably be a Corporal or maybe even a Sergeant. Better chances to move off base if you are single - still and not married.
Best wishes,
Larry Smith
Senior Master Sergeant, USAF (Ret.)
First Sergeant