Mortgage Interest Deduction Calculator: Tax Savings From the Deduction
Work out the federal tax savings from deducting mortgage interest — the headline tax benefit of homeownership, and one of the largest itemized deductions for most homeowners who use it.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Annual tax savings | After-tax interest cost |
|---|---|---|
| 24% bracket · $12k interest | 2,880 | 9,120 |
| 32% bracket · $20k interest | 6,400 | 13,600 |
| 12% bracket · $8k interest | 960 | 7,040 |
| 37% bracket · $35k interest | 12,950 | 22,050 |
How This Calculator Works
Enter your marginal federal tax rate and the annual mortgage interest you paid (from Form 1098). The calculator multiplies the two to give the tax savings and shows the after-tax cost of the interest. The savings only apply if you itemize; the standard deduction has made itemizing less common since 2017.
The Formula
Percentage of an Amount
Amount is the base value, Percentage is the rate applied to it
Worked Example
Paying $12,000 of mortgage interest at a 24% marginal tax rate saves $2,880 in federal tax — making the after-tax interest cost $9,120 rather than the full $12,000. Add state tax savings (typically 3% to 9% more) for the all-in figure.
Key Insight
The mortgage interest deduction is worth far less than most buyers expect, for two reasons. First, the 2017 TCJA roughly doubled the standard deduction — many homeowners now save more by taking the standard than by itemizing mortgage interest. Second, the deduction only saves the marginal rate × interest — not interest × 100%. A $12,000 interest bill at 24% bracket saves $2,880, not anywhere near $12,000.
Frequently Asked Questions
How is the mortgage interest deduction savings calculated?
Multiply annual mortgage interest by your marginal tax rate. $12,000 of interest at a 24% rate saves $2,880 in federal tax.
Do I get the deduction if I take the standard deduction?
No — the mortgage interest deduction is an itemized deduction. You can only take it if total itemized deductions exceed the standard deduction. For 2024 the standard deduction was $14,600 (single) / $29,200 (married filing jointly), which has made itemizing much less common.
Is there a cap on deductible mortgage interest?
Yes. The Tax Cuts and Jobs Act capped deductible interest at the first $750,000 of mortgage principal for loans originated after 12/15/2017. Older loans ('grandfathered') keep the previous $1 million cap.
What about state income tax savings?
Most states with income tax also allow some version of the deduction (or follow federal itemization). Add your state marginal rate to federal for the total tax-rate savings — typically 3% to 9% more in tax-relevant states.
Should I keep the mortgage longer for the deduction?
Usually no. The deduction returns marginal rate × interest, not 100% of interest. Paying $12,000 of interest to save $2,880 in tax still costs $9,120 net. Paying off the mortgage saves the whole $12,000.
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Methodology & Review
Tax savings is annual mortgage interest multiplied by the marginal tax rate. The deduction only applies if you itemize — the savings shown is the marginal benefit beyond the standard deduction. The Tax Cuts and Jobs Act capped deductible interest at the first $750,000 of mortgage principal (post-2017 loans).
Written by Ugo Candido · Last updated May 17, 2026.