"People (often) don't get much help on their tax returns in the year they purchase a home, because they have deductible interest and taxes for only part of a year, and they might not even qualify to itemize," said Mark Luscombe, a principal tax analyst for CCH.

The credit is refundable, so it will help even those people with little or no tax liability.

But there's a big drawback: The credit eventually has to be repaid, although you have 15 years to do it. This feature basically makes it an interest-free loan from Uncle Sam, payable in $500 annual installments.

If you sell, move out or otherwise stop using the home as your primary residence, you'll need to repay any remaining credit balance in the same year.

"Someone thinking of buying a house, taking the credit and renting out the house in a couple years after moving to a new principal residence...shouldn't," said Kamman.

There's also a provision that would bar you from taking the credit if you sell or otherwise dispose of a home during the same year you apply for the credit. Nor is the tax break available to nonresident aliens.

In short, repayable credits aren't as good as straight credits, but they're certainly attractive to buyers who can qualify and sort everything out.

Once again, the government is dangling incentives to get people into homes, offering just about everything but the kitchen sink.