The following calculator can be used to estimate the home mortgage interest deduction of a year (Line 8e on Tax Form 1040 Schedule A).
The calculator only estimates the home mortgage interest deduction and is useful for planning purposes only. The result is likely different from the exact number you need to fill in your tax form due to various details and nuances required by the tax law. Instead, when filling in your tax form, please follow the relevant instructions or hire a tax professional.
- Year-Beginning Loan Balance: The mortgage balance at the beginning of the year. You can typically find it in the last mortgage statement of the year before the year of interest or the first statement of the year of interest.
- Annual Interest Rate: The annual interest rate of the mortgage loan.
- Monthly Payment: The monthly payment of the mortgage loan.
- Additional Payment Per Month: Additional payment you pay in additional to the monthly payment. This is likely zero if you don’t know what this is.
- Max Deductible Principal: The maximum principal of which the interest is deductible. This is typically $750,000 if the mortgage loan was secured on or after December 16, 2017, or $1,000,000 if the mortgage loan was secured on or before December 15, 2017. Please refer to IRS Pub 936 for details.
- Mortgage Length (in Months) in the Year: The number of months that the mortgage loan lasts for the year of interest. This is usually 12, unless the mortgage loan is originated or terminated (e.g., selling the house) in the year of interest. If the mortgage loan is paid off in the year of interest by Monthly Payment and Additional Payment per Month, you can leave this field as 12, because the calculator is able to figure out the length of the mortgage loan in the year of interest in this case.