In addition to the Federal Tax Incentives many utility companies and state governments offer tax incentives for replacing inefficient windows and doors. I recently ran across a great website that lists all the available incentive programs by state. Included in the database are incentives for both commercial and residential buildings. To see if there are any incentive programs you qualify for please visit: http://www.dsireusa.org/
If you find that you qualify for an incentive program make sure you understand the requirements and order your products accordingly. When ordering windows make sure you know what U-Value is required to qualify for the credit. In most cases, off the shelf windows will not meet the requirements for qualifying for incentive programs so make sure you clarify with your sales professional whether t windows or doors will meet tax credit requirements.