Can I treat purchase as if it occured in 2008 or 2009?

For a home purchase in 2009, you can treat as if it happened in 2008 or 2009. If the applicable income phaseout would reduce your home buyer tax credit amount in 2009 and a larger credit qould be available using the 2008 MAGI amounts, then you can choose the year that yields the largest credit amount

Modified Adjusted Gross Income (MAGI) Limit for tax credit qualification

If MAGI is above the limit, do you qualify for tax credit?

Possibly. It depends on your income. Partial credits of less than $7,500 are available for some taxpayers whose MAGI exceeds the phaseout limits. The credit becomes totally unavailble for individual taxpeyers with modifiyed adjusted gross income of more than $95,000 and for married taxpayers filling joint returns with an AGI of more than $170,000

Tomorrow, I will cover how partial credit is calculated...