First of all, your friend should come here asking the question him/herself.
Generally speaking, this raised a red flag during IRS audit because somebody else claimed the exactly same deduction again. TR163 says it all. A taxpayer can claim this deduction for as long as the mortgage is his OWN indebtness.
In another words, IRS does not who is the owner and whose name is on the title. TR163 alllows a legal or equitable owner to claim this deduction under two conditions. One, the taxpayer must own the house somehow, legally or equitably. Your friend meets this requirement. Second, the taxpayer must actually paid the mortgage. He or she does not have to be on the loan, but must actually paid the mortgage payment, principle pluse interest, to be able to claim mortgage interest deduction. What IRS is trying to prevent is your friend claimed the deduction but did not pay a thing for the mortgage debt.
If your friend actually made the mortgage payments, let him or her prepare the actual statements, cancelled checks, etc.to show to IRS. Do not just show IRS the TR163 for they know the code.
