The very popular $8,000 mortgage tax credit for first-time Maine home buyers (and $6,500 for repeat buyers) is due to expire June 30. And if you haven’t already signed a contract, you’ve missed the boat – all contracts must have been signed by April 30 and the loans have to close by the end of June. That is, unless Congress passes a proposal currently in the Senate, sponsored by Majority Leader Harry Reid (D-Nev.), which would allow buyers three more months to close, with a deadline of Sept. 30. Apparently, the tax credit has been so enticing that it has created a backlog of loans for lenders, and some, including the National Association of Realtors, worry that the high volume of contracts as well as the nature of foreclosure and short sales could mean many Maine buyers would miss the closing deadline and miss the tax credit they were clearly trying to take advantage of.