You two will have to work this out. But here's your options based on tax law.
- In order to claim/deduct the mortgage interest, you must have a legal obligation to pay it. So if you both signed the mortgage, that's fine. It doesn't matter that only one of you is named on the 1098. So weather one of you claims it, or you split it doesn't matter. But be aware that legally speaking, there's actually two criteria that needs to be met.
1) You must be legally obligated to pay it.
2) You must have actually paid what you claim you paid.
The same holds true for the property taxes also.
