My motto "When in doubt - FILE". The statute of limitation does not even begin to run until the return is filed. Even if the 2010 is a simple little return, it is nice to close the door on that chapter of the clients life. This will also confirm that no one used the clients SSN to file a fraudulent tax return. DO YOU HAVE TO? Maybe not, but do it anyway. They have indirectly asked you for a professional answer, which I think is yes.