@IRonMaN Don't hurt yourself jumping to conclusions.  My first question would be whether he's a US citizen, and if so for how long.  He may have a green card and has just discovered that part of the citizenship application process involves a check of tax compliance.  Or, he may have been in this country less than 10 years and just discovered that he is not eligible for Social Security benefits (and maybe Medicare?).  

Or is he a retired first responder, with 40 years of service not covered by Social Security?  Granted, his benefits would be reduced because of the public-service pension, unless he has deferred collecting that until after SS benefits begin.  (I know, he's supposed to report that, but how many retirees do?)  

Without knowing any of the facts and circumstances, my advice would be to collect a few of those before turning away an honest man.