Per IRS Publication 936 at https://www.irs.gov/publications/p936 you can claim qualified deductions (basically, mortgage interest and property taxes on a primary residence/2nd home, and that's it) if two conditions are met.
1. You have a vested interest in the property
2. You actually pay the expense you are claiming.
There is nothing that says your name has to be on anything - mortgage loan papers, property deed, nothing. Though in some situations it can make it difficult to prove that vested interest if audited.
