For tax year 2017, for example, if your income exceeds $287,650 (for married couples filing jointly, it’s $313,800), you lose some of your Schedule A itemized deductions (which includes mortgage interest and property taxes, too).
Also, be aware of the following standard mortgage tax deductions: $12,700 for married couples and $6,350 for singles for tax year 2017. Ignoring your mortgage interest deductions, if your itemized deductions total less than these threshold amounts, some of your mortgage interest is effectively not tax deductible.
For example, if you’re married and your itemized deductions, excluding mortgage interest, total to $10,000, then $2,600 of the mortgage interest you pay is essentially not tax deductible because you automatically qualify for the standard $12,600 deduction if you elect not to itemize.Last but not least, IRS tax laws limit the amount of mortgage interest on your primary and a secondary residence that’s tax deductible to no more than the interest on up to $1 million of mortgage debt. Also, the interest is allowed to be deducted only on debt equal to the amount you borrowed when you originally bought your home plus $100,000.