As long as they don't loose or change jobs. If you lose your job, or change employers, you must pay back the loan in full within a short period, often 60 days. If you dont, it is treated as a withdrawal and subjected to the same taxes and penalties. 401K accounts can usually be rolled over into 401K accounts at a new employer, or into an IRA, without triggering tax payments or penalties, but loans from a 401K cannot be rolled over.