You own a home and are thinking of doing some home repairs. This year there is a tax credit of one-fifth the cost of materials for adding insulation and for replacing windows and external doors, up to a $4,000 tax credit maximum.

a. You decide to add insulation to your attic which costs $2,800 in materials, and you install it yourself. What is the dollar amount of the tax credit?

b. You are in a 28% tax bracket. How much does the home-repair tax credit reduce your tax liability?

c. How much would you have to spend on qualified improvement materials to maximize your $4,000 tax credit?