Per the IRS, in order to deduct property taxes and mortgage interest you generally must be legally obligated to pay the expense and must have paid the expense during the year.
https://www.irs.gov/faqs/itemized-deductions-standard-deduction/other-deduction-questions/other-dedu...
Note: If the expenses were paid out of a joint account, you can generally split the deduction any way you want - since there is no way to determine whose dollars were used.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
