Mortgage Interest Deduction Calculator
Mortgage interest is deductible when you itemize — but only on the first $750,000 of acquisition debt, and only if your total itemized deductions beat the 2026 standard deduction. This calculator estimates your year-one interest, compares the two paths, and shows the tax saved.
How to use this calculator
- Enter outstanding mortgage balance.
- Enter interest rate.
- Enter filing status.
- Enter other itemized deductions (SALT, charity, etc.).
- Enter taxable income.
- Your results appear instantly below and update as you change the numbers.
How this calculator works
Interest is approximated as your balance times your rate for year one (it declines each year as you pay down principal). Only the interest on the first $750,000 of acquisition debt counts, and it only helps if itemizing beats the standard deduction — $16,100 for single filers, $32,200 for joint. The tax saved is the extra deduction times your marginal tax bracket.
Frequently asked questions
Does my whole mortgage payment count?
No — only the interest portion, not principal, taxes, or insurance. In the early years of a 30-year loan most of the payment is interest; by the end, most of it is principal.
What if my mortgage is over $750,000?
Interest is still deductible, but only on the first $750,000 of acquisition debt (the 2026 limit). A $1,000,000 loan gets the deduction on 75% of its interest.
I took the standard deduction last year — should I itemize now?
Run the standard-vs-itemized calculator with your real numbers. Under the 2026 rules, a typical $350k loan at 6.5% ($22,750 of interest) alone often beats the single standard deduction but can fall short for joint filers without other deductions.
Disclaimer: Results are estimates for general information only and do not constitute financial, tax, or legal advice. Figures reflect 2026 rules and may change. Always confirm current limits and consult a qualified professional before making decisions. Official figures: IRS.gov · 2026 limits per IRS tax inflation adjustments.