My mortgage interest deduction?
Type the mortgage interest you paid, your average loan balance, and your income. The answer is the deductible interest and how much federal tax it saves over the standard deduction.
- Deductible mortgage interest
- $20,000.00
Of $20,000.00 of mortgage interest, $20,000.00 is deductible, saving $3,492.00 of federal tax.
- Federal tax it saves
- $3,492.00
- Debt limit
- $750,000.00
- Share deductible
- 100%
- Itemized deductions
- $32,000.00
- Standard deduction
- $16,100.00
- Itemizing beats the standard deduction by
- $15,900.00
- Best choice
- Itemize
Deductible mortgage interest: $20,000.00. Of $20,000.00 of mortgage interest, $20,000.00 is deductible, saving $3,492.00 of federal tax.
Federal tax it saves by mortgage interest paid
The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use
How to calculate
Works out how much of your 2026 home mortgage interest is deductible under the $750,000 (or $1 million) debt limit, and how much federal tax it saves over the standard deduction.
Example with the default inputs (Mortgage interest paid $20,000.00, Average mortgage balance $400,000.00, Loan taken out After December 15, 2017, Filing status Single, Income $120,000.00, Other itemized deductions $12,000.00): Of $20,000.00 of mortgage interest, $20,000.00 is deductible, saving $3,492.00 of federal tax.
Method: Limit = $750,000 for debt taken out after December 15, 2017, $1,000,000 for older debt (half each when married filing separately). If the average balance is over the limit, deductible interest = interest × (limit ÷ balance, rounded to three places); otherwise all of it. Tax saved = Form 1040 tax with your other itemized deductions − tax with them plus the deductible interest, each taking the larger of the standard and itemized deduction.
- An estimate for tax year 2026 (IRS Publication 936, Rev. Proc. 2025-32), not tax advice.
- All the debt was used to buy, build, or substantially improve the home; interest on home equity debt used for anything else is not deductible. Points and mortgage insurance premiums are not included.
- Income is ordinary income with no credits; your other itemized deductions are already within their own limits.
Worked examples
Each example is checked against the calculator on every build.
- Mortgage interest paid $20,000.00, Average mortgage balance $400,000.00, Loan taken out After December 15, 2017, Filing status Single, Income $120,000.00, Other itemized deductions $12,000.00 gives Deductible mortgage interest $20,000.00, Federal tax it saves $3,492.00, Itemizing beats the standard deduction by $15,900.00.Source: IRS Publication 936: under the $750,000 limit all interest is deductible
- Mortgage interest paid $60,000.00, Average mortgage balance $1,000,000.00, Loan taken out After December 15, 2017, Filing status Married filing jointly, Income $400,000.00, Other itemized deductions $40,000.00 gives Deductible mortgage interest $45,000.00, Share deductible 75%.Source: IRS Publication 936 Table 1 lines 11 to 15: 750,000 ÷ 1,000,000 = 0.750
- Mortgage interest paid $48,000.00, Average mortgage balance $1,200,000.00, Loan taken out October 14, 1987 to December 15, 2017, Filing status Married filing jointly, Income $400,000.00, Other itemized deductions $40,000.00 gives Deductible mortgage interest $39,984.00, Debt limit $1,000,000.00.
- Mortgage interest paid $25,000.00, Average mortgage balance $500,000.00, Loan taken out After December 15, 2017, Filing status Married filing separately, Income $150,000.00, Other itemized deductions $5,000.00 gives Deductible mortgage interest $18,750.00, Debt limit $375,000.00.
How it works
- Debt limit: $750,000 for debt taken out after December 15, 2017, or $1,000,000 for debt from October 14, 1987 to December 15, 2017. Married filing separately: $375,000 or $500,000.
- If the average balance is at or below the limit, all the interest is deductible.
- If it is above the limit (Publication 936 Table 1): share = limit ÷ average balance, rounded half up to three decimal places; deductible interest = interest × share. The arithmetic is exact on the amounts you type.
- Itemized deductions = deductible interest + other itemized deductions, less the IRC 68 cut: 2/37 of the lesser of them and income over the start of the 37% bracket ($640,600 single and head of household, $384,350 married filing separately, $768,700 jointly or surviving spouse). Itemizing beats the standard deduction by the itemized deductions less the standard deduction, or 0; the best choice is to itemize when that is above 0.
- Tax saved: two 2026 Forms 1040 with your income as ordinary income and no credits, one with the other itemized deductions alone and one with the deductible interest added. Each takes the larger of the standard deduction ($16,100 single or separately, $32,200 jointly or surviving spouse, $24,150 head of household) and the itemized deductions, then the Tax Table below $100,000 of taxable income (the rate schedule at the middle of the $50 row, rounded to whole dollars) or the rate schedule above. Tax saved = tax without − tax with.
When the data is out of date
The debt limits do not change each year, but the standard deduction and brackets do. After the 2026 filing season the page keeps using the 2026 tables and says so above the result.
Worked examples by hand
Single, $120,000 of income, $12,000 of other itemized deductions, $20,000 of interest on a $400,000 loan. The balance is under $750,000: $20,000 is deductible. Itemized $32,000 beats $16,100 by $15,900. Without the interest: 120,000 − 16,100 = $103,900 taxable, rate schedule 1,240 + 4,560 + 22% × 53,500 = $17,570. With it: 120,000 − 32,000 = $88,000, Tax Table row middle $88,025: 1,240 + 4,560 + 22% × 37,625 = 14,077.50, so $14,078. Tax saved $3,492.
A $1,000,000 average balance and $60,000 of interest, loan from 2020. 750,000 ÷ 1,000,000 = 0.750; 0.750 × 60,000 = $45,000.
A $1,200,000 average balance from 2015 and $48,000 of interest. 1,000,000 ÷ 1,200,000 = 0.8333, rounded to 0.833; 0.833 × 48,000 = $39,984.
Other questions people ask
How much mortgage interest can I deduct?
Interest on up to $750,000 of home acquisition debt ($375,000 married filing separately) for loans taken out after December 15, 2017, or up to $1 million ($500,000) for older loans (IRS Publication 936). If your balance is over the limit, you deduct the share of interest the limit covers.
Do I need to itemize to deduct mortgage interest?
Yes. Mortgage interest is an itemized deduction on Schedule A. It saves tax only when your itemized deductions add up to more than the standard deduction: $16,100 single, $32,200 married filing jointly, $24,150 head of household in 2026.
How much tax does the deduction save?
Only the part of your itemized deductions above the standard deduction saves tax, at your top rate. For example, if itemizing beats the standard deduction by $10,000 and you are in the 22% bracket, you save about $2,200.
What loans count?
Loans secured by your main home or one second home and used to buy, build, or substantially improve it. A home equity loan or line of credit counts only to the extent you used it to improve the home.
How is the deductible share figured when the loan is over the limit?
Publication 936 Table 1 divides the limit by your average balance, rounds the result to three decimal places, and multiplies your interest by it. A $1 million average balance with $60,000 of interest gives 0.750 × 60,000 = $45,000.
Why do older loans have a higher limit?
The 2017 tax law cut the limit from $1 million to $750,000 for debt taken out after December 15, 2017. Loans from before then keep the $1 million limit ($500,000 separately), as does a home bought before April 1, 2018 under a written binding contract made before December 15, 2017 to close before January 1, 2018 (Publication 936).