Mortgage interest and property taxes are itemized deductions. And every tax return is allowed to utilize either their itemized deductions or the standard deduction. For 2018, the standard deduction amounts were increased significantly to $12,000 for single/MFS, $18,000 for head of household, and $24,000 for a joint return. Therefore, in order for your return to benefit from itemized deductions, the total of the itemized needs to be more than the standard deduction amount.
When income is first entered into TurboTax, the standard deduction amount is applied. Therefore, when you are entering in itemized deduction amounts, your tax due or refund amount will not change until the itemized total exceeds the standard deduction, as the standard deduction is already applied to the return. See more information below:
https://ttlc.intuit.com/replies/4848485
