Like JAFO said.

Since you're both on the title and responsible for the payments, whoever pays gets the deduction. It may very well be to your advantage for one of you to make all the deductible payments while the other uses the standard deduction and pays nondeductible expenses like food, utilities, maintenance, etc. You really just need to sit down and pound some numbers. One of the tax software programs would be useful for this.

The important thing is that you need to do this before the payments are made. Should IRS ever come to inquire, you'd want to be able to show that the person(s) claiming the deductions actually paid. If you decide that one person is going to claim them, pay them from separate funds. If you're going to split, you can pay from a joint account, but I'd make sure that the account is funded in the same percentages as the deductions.

Phil Marti
VITA Volunteer