Fr Chuck is correct. The debt needs to be secured by a qualifying residence. See the following information:
http://www.irs.gov/publications/p936/ar02.html#d0e182
Generally, home mortgage interest is any interest you pay on a loan secured by your home (main home or a second home). The loan may be a mortgage to buy your home, a second mortgage, a line of credit, or a home equity loan.
You can deduct home mortgage interest only if you meet all the following conditions.
You must file Form 1040 and itemize deductions on Schedule A (Form 1040).
You must be legally liable for the loan. You cannot deduct payments you make for someone else if you are not legally liable to make them. Both you and the lender must intend that the loan be repaid. In addition, there must be a true debtor-creditor relationship between you and the lender.
The mortgage must be a secured debt on a qualified home. “Secured debt” and “qualified home” are explained later.
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Secured Debt
You can deduct your home mortgage interest only if your mortgage is a secured debt. A secured debt is one in which you sign an instrument (such as a mortgage, deed of trust, or land contract) that:
Makes your ownership in a qualified home security for payment of the debt,
Provides, in case of default, that your home could satisfy the debt, and
Is recorded or is otherwise perfected under any state or local law that applies.
In other words, your mortgage is a secured debt if you put your home up as collateral to protect the interests of the lender. If you cannot pay the debt, your home can then serve as payment to the lender to satisfy (pay) the debt. In this publication, mortgage will refer to secured debt.
Debt not secured by home. A debt is not secured by your home if it is secured solely because of a lien on your general assets or if it is a security interest that attaches to the property without your consent (such as a mechanic's lien or judgment lien).
A debt is not secured by your home if it once was, but is no longer secured by your home.