So my brother is in a unique situation where he was married by common-law married in Colorado with his now ex wife of this year (2013) but his name was never on their house loan when they received the 2009 tax credit of $8000. They ended up moving out of the house when they needed to live in the house for at least three years to maintain the credit and now the government wants the credit back since the rule was broken.

His ex wife claims that he owes $4000 for the credit even though his name was never on the loan and the credit went into the house that her and her father owns. The catch is that my brother and her always filed jointly then they had their son in 2006. Also in the divorce decree it says that the house is hers and her father only and my brother owns none of it. Does he owe? Please help!