All of the information required on that form is public information already available if 'they' want to "dig" for it. It is just easier (cheaper) to ask you for it. And it's a possible way of eliminating confusion. I had a cousin with the same name as mine except for a middle initial. I use that middle initial! But I wish I had a penny for every time people have gotten us confused. (I wonder how many Mike Tysons there are?) Legal names are exactly that. You may not like your name and use a contraction or nick-name, but that legal name is the only one binding. The biggy about any of this is that off I want any public information about you... I can get/buy it.