Mortgage Interest Deduction Calculator
Estimate the tax value of your mortgage interest deduction, including the $750,000 acquisition-debt limit and your marginal rate.
How it works
Deductible interest = balance × rate × min(balance, $750,000) ÷ balance · Tax savings = deductible interest × marginal rate
Mortgage interest on up to $750,000 of home-acquisition debt is deductible if you itemize. The tax benefit equals the deductible interest multiplied by your marginal tax rate, not the full interest — a common overestimate. Crucially, the deduction only helps to the extent your total itemized deductions exceed the standard deduction, so many homeowners get less benefit than the headline figure suggests.
Worked example
On a $400,000 loan at 6.5%, annual interest is $26,000. The whole balance is under the $750,000 cap, so all $26,000 is deductible; at a 24% marginal rate that is worth about $6,240 in tax savings.
Frequently asked questions
How much mortgage interest is deductible?
Interest on up to $750,000 of home-acquisition debt (or $1 million for loans taken before December 16, 2017) is deductible when you itemize. Interest on debt above the cap is not.
Does the deduction save me the full interest amount?
No. It reduces taxable income, so the benefit is the deductible interest times your marginal tax rate — for example 24%, not 100%, of the interest.
Do I need to itemize to benefit?
Yes. The deduction only helps if your itemized deductions, including this interest, exceed your standard deduction. Otherwise you get no extra benefit from the mortgage.
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Educational estimate, not tax advice. Uses recent federal parameters that change yearly and ignores your full situation — confirm with a tax professional or the IRS.