Thought the same thing my first couple reads through - it's rather hidden...
Core said:
Benefits are gained when a character leaves a career for any reason other than failing a survival roll (willingly leaving the career, an event, an aging crisis, or just wishing to finish character generation).
So, between terms - though an advancement roll of natural 12 can force staying in (had that happen when intentionally trying to gen an older PC, only to end up 8 years older than intended!).
