As a result of the stimulus bill, homeowners can claim a tax credit of up to $1,500 for upgrading their primary residence with energy efficient appliances and building components, such as exterior windows, doors and skylights. This way, homeowners can reduce their income tax by up to thirty percent of the purchase price (not including installation costs) of qualified products installed in 2010.  In order to qualify, windows, doors, and skylights must be accompanied with a signed statement from the manufacturer that certifies that the product complies with the tax credit criteria. Qualified windows, doors, and skylights need to have NFRC-certified U-factor and Solar Heat Gain Coefficient (SHGC) ratings that do not exceed 0.30.