There's only two things that can be claimed on a tax return for this. Mortgage interest reported to the primary borrower on the loan on a 1098-Mortgage Interest Statement, and property taxes. That's it.
To claim both or either, two criteria must be met.
1) You must be legally obligated to pay it.
2) You must have actually paid it.
So regardless of whose name/SSN is on 1098 or property tax bill, if you meet both criteria above you can claim those two items.
Both property taxes and Mortgage interest are a SCH A deduction that will have no impact what-so-ever on your tax liability until the total of all SCH A deductions exceeds your standard deduction.
