Congress is moving closer to extending the life of a home-buyer tax credit scheduled to expire at the end of this month.

"It appears increasingly likely that Congress will extend the home-buyer tax credit, especially in light of the persistent weakness in the economy," says Tim Hanford, tax consultant with ADC Strategies in Bethesda, Md., and a former House Ways and Means Committee tax staffer.

Support also appears to be growing for expanding the provision, such as by offering a reduced credit to many homebuyers who aren't eligible for the existing one. Final details are expected soon.

Since Congress still hasn't finished work on the legislation, some buyers are wondering whether to rush to close deals before the end of this month in order to nail down their credit. "If at all possible, it would be best to try to complete a home purchase before the end of November," says Mr. Hanford. "But don't be in such a rush that you end up overpaying because that could wipe out some or all of the benefit of the credit."

The credit amount is 10% of a home's purchase price, with a maximum of $8,000 for a single taxpayer and a married couple filing a joint return. The limit is $4,000 for a married person filing a separate return.

The credit generally is available to home buyers with modified adjusted gross income below certain amounts, and who have never owned a home or haven't owned one in the past three years. For married couples filing jointly, that ownership requirement "applies to both spouses," the Internal Revenue Service says.

Also, the credit applies only to the purchase of a principal residence located in the U.S., according to the IRS. Vacation homes and rental properties "are not eligible," an IRS statement says.

The credit reduces your tax bill or increases your refund, on a dollar-for-dollar basis. It also is "fully refundable," meaning eligible taxpayers will get the credit even if they don't owe any tax, or if the credit is more than the tax they owe. Taxpayers can claim the credit on returns for either 2008 or 2009.

For more of the fine print, read Form 5405 at www.irs.gov.