I can't speak to the legality, but I've counseled student loan borrowers for 12 years and have never encountered a scenario where fees were imposed or back-interest was assessed in a scenario like this. I have seen this happen many times, and it usually occurs because your last school never reported your separation date. You may want to check on this at http://www.NSLDS.ed.gov
. After logging in, you will see all of your federal loans listed. A code will tell you why they are deferred (IS for "in-school", GR for "grace" etc) and should also list the estimated date that repayment will begin.