Update: This deduction expired at the end of 2016 and has not been renewed as yet. It is not available on 2017 tax returns.
Insulation qualifies for a credit of 10% of the cost of the materials (not including installation and labor) with a lifetime maximum of $500. The home energy efficiency credits are listed in the Your Home section of the deductions and credits page. If you don't see it you may need to click something like "show me more choices".
