Did you buy in 2008?
You have to repay the credit you received for your 2008 home purchase over a 15 year period. Your first payment is due with your 2010 tax return.
If you move from the home that you purchased in 2008 you’ll have to repay the balance of your credit in the year you move. You’ll have to stay where you are for 15 years if you intend to repay over 15 years.

Did you buy in 2009, 2010 or 2011?
Generally, if you don’t stay where you are for 36 months after you purchased the home, you’ll have to repay the credit in the year you move. There are exceptions for death, destruction and divorce, and we’ll help you during these tough times.

Of course, this is just a guideline.. You should talk to a tax professional to verify this information applies to you!