You may deduct the interest on the first $1 million of mortgage debt as well as all the property taxes. (This mortgage interest deductibility covers debt on both your primary residence and a second residence.) The IRS also allows you to deduct the interest costs on additional borrowing known as home equity loans or home equity lines of credit to a maximum of $100,000 borrowed.
To keep things simple and get a reliable estimate of the tax savings from your mortgage interest and property tax write-off, multiply your mortgage payment and property taxes by your federal income tax rate. This approximation method works fine as long as you’re in the earlier years of paying off your mortgage, because the small portion of your mortgage payment that isn’t deductible (because it’s for the repayment of the principal amount of your loan) approximately offsets the overlooked state tax savings.
| Singles Taxable Income | Married-Filing-Jointly Taxable Income | Federal Tax Rate (Bracket) |
| Less than $9,325 | Less than $18,650 | 10% |
| $9,325 to $37,950 | $18,650 to $75,900 | 15% |
| $37,950 to $91,900 | $75,900 to $153,100 | 25% |
| $91,900 to $191,650 | $153,100 to $233,350 | 28% |
| $191,650 to $416,700 | $233,350 to $416,700 | 33% |
| $416,700 to $418,400 | $416,700 to $470,700 | 35% |
| More than $418,400 | More than $470,700 | 39.6% |