My husband in a citizen of the United Kingdom, and I am a US citizen. We live in the UK. We were married two years, but I'm uncertain as to whether I should file my 2011 taxes as single or married. This is because we are married though a same-sex civil partnership here in the UK. As I understand it, the Federal government doesn't recognise this type of partnership and neither does my state (NC). So does this mean I should file single?