Members of the military and certain other federal employees serving outside the U.S. have an extra year to buy a principal residence in the U.S. and qualify for the $8000 credit. Thus, an eligible taxpayer must buy, or enter into a binding contract to buy, a principal residence on or before April 30, 2011. If a binding contract is entered into by that date, they need to close by June 30, 2011. Members of the military and members of the Foreign Service and employees of the intelligence community are eligible for this special rule. It applies to any individual (and, if married, the individual's spouse) who serves on qualified official extended duty service outside of the United States for at least 90 days during the period beginning after Dec. 31, 2008, and ending before May 1, 2010.