I have a modest mortgage and a modest car loan. My credit is AAA awesome. I make about $75000 gross a year. Recently I was approached by a doctor when I mentioned my credit was excellent about co-signing for a mortgage refinance of about $400,000 for 20 years. He states making $450,000 a year and does seem to have a bright future to make more it seems. I assume he is trying to utilize the equality from the home. He explained I could save him lots of interest since my FICA was so awesome and because of my risk and assistance he would offer in return a lawyered up agreement and once the mortgage was put through, he would cut me a check for anywhere from $10,000 - $15,000. Does this sound too good to be true. Would I have to consider this income and pay taxes? And how many other concerns should I have? The money would pay my car off which makes it tempting but I do not want to do anything illegal or foolish.