I had a question recently which I didn't know the answer to. It was "can you buy a 2 family home and qualify for the $8,000 tax credit. Everything I have seen about the credit said that it applied to one family homes, condos, co-ops, house trailers and even house boats as long as it was your primary residence, but I never saw anything on 2 families. So I searched the IRS web site and discovered that 2 families do qualify as long as it's your primary residence. Here is the answer that I found on http://www.irs.gov/newsroom/article/0,,id=206291,00.html
Q. I purchased a duplex home with two separate dwelling units. I will live in one dwelling and will rent out the other dwelling unit and report the rental income on Schedule E. May I qualify for the first-time homebuyer credit, and what amount do I use for the purchase price to determine the amount of the credit?
A. Yes, you may qualify for the credit for the dwelling unit that you use as your principal residence. To determine the amount of your credit, you must allocate the purchase price of the duplex between the two separate dwelling units. Your credit is 10% of the portion of the purchase price of the duplex allocated to your dwelling unit that you use as your principal residence, up to a maximum credit of $8,000. You may not use the entire purchase price of the duplex to determine the amount of your credit.