Since you did not make any payments (mortgage interest or principal) in 2020, do not take a deduction for mortgage interest in 2020. Complete the Form 1098 interview and enter "0" in the "Mortgage interest paid" field.
As individuals, you are considered "cash-basis" taxpayers. You only owe tax on income you receive and can only claim a deduction for items that have been paid during the tax year in question.
