The tax credit for energy efficient replacement windows and doors was introduced in 2009 as part of the American Recovery and Reinvestment Act. It will expire, however, at the end of 2010. Accordingly, this may be a good time for homeowners to replace their windows.
The federal government established fairly stringent guidelines for windows to qualify for the tax credit.
For example, replacement windows must have a U-Factor rating of .30 or lower and a Solar Heat Gain Coefficient rating of .30 or lower.