The US wind industry has passed a major hurdle with the passing of the extension. The provision extends the deadline to start construction of qualifying renewables projects from the end of this year to the end of 2011.
It is part of broader tax bill whose main focus is the extension of expiring tax cuts instituted during the administration of President George W. Bush.
The legislation was signed off by the US Senate on Monday.
Democrats have complained the legislation favours the wealthy and many want alterations to package, but Republicans have cautioned that making changes at this stage risks the entire deal.
Denise Bode, CEO of the American Wind Energy Association, said: "This is a great holiday present for the 85,000 American workers in the wind energy industry, tens of thousands of whom will now be able to get back to work in a sector that has been a bright spot in the recession so far.
"Orders will be on the rise for new wind power, and investors will put more capital into the U.S. economy because of what happened in Congress last night."