The Mortgage Interest Deduction May Be a Great Tax Planning tool as long as you understand what you are working with. Qualified Home In order to use the mortgage interest deduction, the mortgage must be secured by a Qualified Home: Main home. You can have only one main home at any one time. This is the home where you ordinarily live most of the time. Second home. A second [Read more...] about A Deeper Look at the Mortgage Interest Deduction During Equity Buy Out