Mortgage Interest Deduction Calculator

Determine if itemizing your mortgage interest deduction saves more than the standard deduction. Calculate the actual tax savings.

Mortgage & Tax Details

$

Max deductible on $750,000.00

$

From Form 1098

%

Your highest federal tax bracket

$

$14,600 single / $29,200 MFJ (2024)

$

SALT (max $10K), charity, medical, etc.

Enter your mortgage and tax details to see if itemizing saves you money.

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Pro Tip

Consider 'bunching' your charitable donations into alternate years. Give two years' worth in one year to push your itemized deductions above the standard deduction, then take the standard deduction in the other year.

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Understanding the Mortgage Interest Deduction

The mortgage interest deduction allows homeowners to deduct interest paid on their home mortgage from their taxable income. For mortgages originated after December 15, 2017, interest is deductible on up to $750,000 of mortgage debt ($375,000 if married filing separately).

To benefit from the mortgage interest deduction, your total itemized deductions must exceed your standard deduction. Since the Tax Cuts and Jobs Act of 2017 nearly doubled the standard deduction, fewer taxpayers benefit from itemizing.

Other common itemized deductions include state and local taxes (SALT, capped at $10,000), charitable contributions, and medical expenses exceeding 7.5% of AGI. If these plus your mortgage interest exceed the standard deduction, itemizing saves you money.

The tax savings from the mortgage interest deduction equals the deductible interest multiplied by your marginal tax rate. For example, $20,000 in deductible interest for someone in the 22% bracket saves $4,400 in federal taxes.

Mortgage Interest Deduction Benefit

Net Benefit = (Total Itemized - Standard Deduction) × Marginal Rate

Where:

Deductible Interest = Interest on mortgage balance up to $750,000

Total Itemized = Mortgage interest + SALT + charitable + other

Standard Deduction = $14,600 single / $29,200 MFJ for 2024

Marginal Rate = Your highest income tax bracket

Example

Single filer, $400K mortgage, $24,000 annual interest, 22% bracket:

  • • Deductible interest: $24,000 (balance under $750K)
  • • Other itemized: $8,000 (SALT, charity)
  • • Total itemized: $32,000
  • • Standard deduction: $14,600
  • • Net benefit: ($32,000 - $14,600) x 22% = $3,828

Frequently Asked Questions

What is the mortgage interest deduction limit?
For mortgages originated after December 15, 2017, you can deduct interest on up to $750,000 of mortgage debt ($375,000 if married filing separately). Mortgages originated on or before that date are grandfathered at the old $1 million limit.
Is it always better to itemize with a mortgage?
No. Since the 2018 tax law changes, many homeowners find the standard deduction is larger than their itemized deductions. This is especially true for those with smaller mortgages, lower interest rates, or who live in low-tax states.
Can I deduct mortgage interest on a second home?
Yes. You can deduct mortgage interest on your primary residence and one second home, subject to the combined $750,000 debt limit. The second home can be a house, condo, boat, or RV with sleeping, cooking, and bathroom facilities.
Is HELOC interest deductible?
HELOC interest is deductible only if the funds are used to buy, build, or substantially improve the home securing the loan. Interest on HELOC funds used for other purposes (debt consolidation, vacations) is not deductible.
What other expenses can I deduct when itemizing?
State and local taxes (SALT) up to $10,000, charitable contributions, medical expenses exceeding 7.5% of AGI, casualty losses in federally declared disaster areas, and certain investment expenses. The SALT cap is often the binding constraint for high-tax state residents.