Real estate editor Maryann Haggerty and columnist Elizabeth Razzi respond to a question adapted from a recent online chat.

First-time home buyer: If I buy a house tomorrow, before the housing bill is signed into law, would I be eligible for the new $7,500 tax credit for first-time buyers?

Elizabeth Razzi: Nothing is ever certain until the ink is dry on the president's signature, of course, but, at last read, you would indeed be eligible for the new tax credit. A tax credit equal to 10 percent of the price, or $7,500, whichever is less, will be available to first-time buyers who make their purchase between April 9, 2008, and July 1, 2009.

Maryann Haggerty: You're a first-time buyer under this law if neither you nor your spouse has owned a home for three years before the purchase. The credit applies to the purchase of a principal residence only.

This isn't a no-strings gift -- it's more like a no-interest loan. If you receive the credit, you then pay it back over as much as 15 years. That's known as a recapture. If you sell the house or it is otherwise no longer your principal residence, payback is speeded up.

ER: If you or your spouse has ever qualified for a tax credit for being a first-time buyer in the District, you wouldn't be eligible for this new federal credit. And it's phased out for single buyers whose adjusted gross income exceeds $75,000 or for married buyers who earn more than $150,000.

The next Real Estate Live chat will be 1 p.m. Aug. 8.