IRS Mortgage Interest Deduction Rules – The IRS mortgage interest deduction remains one of the most valuable tax breaks for American homeowners. If you itemize deductions on your federal tax return, you may be able to subtract the interest paid on your mortgage from your taxable income — potentially saving thousands of dollars. This comprehensive guide explains the current IRS mortgage interest deduction rules based on the latest official guidance for tax year 2025 (returns filed in 2026), including debt limits, qualifications, home equity loans, refinancing, and how to claim it correctly.
What Is the IRS Mortgage Interest Deduction?
The home mortgage interest deduction allows eligible taxpayers to deduct interest paid on loans secured by their main home or a second home. It applies only to qualified mortgage interest and requires you to itemize deductions on Schedule A (Form 1040). You cannot claim it if you take the standard deduction.
Generally, home mortgage interest includes interest on mortgages used to buy, build, or substantially improve your qualified home. The deduction is reported on lines 8a, 8b, or 8c of Schedule A, depending on whether the interest appears on Form 1098.
Who Qualifies for the Mortgage Interest Deduction?
To qualify for the IRS mortgage interest deduction, you must meet these key requirements:
- File Form 1040 or 1040-SR and itemize deductions on Schedule A.
- Pay interest on a secured debt (mortgage, deed of trust, or similar) recorded under state law.
- Have an ownership interest in a qualified home (your main home or one second home).
- The loan must be a qualified home mortgage with the intent that it will be repaid.
A qualified home includes a house, condominium, cooperative apartment, mobile home, house trailer, or boat with sleeping, cooking, and toilet facilities. Your main home is where you live most of the time; you can designate only one second home per year.
Mortgage Debt Limits for Tax Year 2025
The IRS places strict limits on the amount of debt that qualifies for the deduction. These limits apply to the combined balance of mortgages on your main home and second home.
- Loans incurred on or before October 13, 1987 (grandfathered debt): Fully deductible with no limit.
- Home acquisition debt incurred after October 13, 1987, but before December 16, 2017: Deductible up to $1 million ($500,000 if married filing separately), provided the total with grandfathered debt stays within the limit.
- Home acquisition debt incurred after December 15, 2017: Deductible up to $750,000 ($375,000 if married filing separately).
If your total mortgage debt exceeds these limits, you can still deduct a proportionate share of the interest using the worksheet in IRS Publication 936. The limits are not indexed for inflation.
What Counts as Qualified Home Mortgage Interest?
Qualified home mortgage interest must meet these tests:
- The loan proceeds were used to buy, build, or substantially improve the home that secures the loan.
- The debt is secured by your qualified home.
- You meet the ownership and filing requirements above.
Points paid to obtain or refinance a mortgage may also be deductible in the year paid (under certain conditions) or amortized over the life of the loan. Mortgage insurance premiums are not currently deductible for tax year 2025.
Rules for Home Equity Loans and HELOCs
Home equity loans and HELOCs follow strict rules under current IRS mortgage interest deduction guidelines:
- Interest is deductible only if the borrowed funds were used to buy, build, or substantially improve the home that secures the loan.
- This rule applies regardless of when the loan was taken out.
- If the proceeds were used for other purposes (e.g., debt consolidation, vacations, or personal expenses), the interest is not deductible.
This change, in effect since 2018, significantly limits the tax benefit of home equity borrowing compared to pre-2018 rules.
Refinancing Your Mortgage and the Deduction
Refinanced loans can qualify as home acquisition debt if:
- The new loan does not exceed the balance of the old mortgage, and
- Any additional proceeds are used to buy, build, or substantially improve the home.
The debt limit depends on the original acquisition date of the refinanced loan. Use IRS Publication 936 worksheets to calculate your qualified loan limit accurately.
How to Claim the Mortgage Interest Deduction on Your Taxes?
- Receive Form 1098 from your lender (sent if you paid $600+ in interest).
- Enter interest reported on Form 1098 on Schedule A, line 8a.
- Report any qualified interest or points not on Form 1098 on lines 8b or 8c.
- If your total debt exceeds the limits, complete the Worksheet to Figure Your Qualified Loan Limit and Deductible Home Mortgage Interest in Publication 936 (Part II).
Keep records of loan documents, use of proceeds, and average debt balances. Average balance can be calculated using the average of the first and last balances or the interest paid divided by the interest rate.
Common Mistakes to Avoid with Mortgage Interest Deduction
- Claiming interest on home equity debt used for non-home purposes.
- Forgetting to allocate interest when part of the home is used for business or rental.
- Deducting more than the debt limit allows without using the IRS worksheet.
- Claiming the deduction without itemizing (it does not apply to the standard deduction).
- Missing the binding contract exception for loans near the December 15, 2017 cutoff date.
Recent Changes and What to Expect in 2026
The core IRS mortgage interest deduction rules for tax year 2025 remain consistent with recent years. Publication 936 (2025) confirms the $750,000 / $1 million debt limits and the expiration of the mortgage insurance premiums deduction.
Recent legislation (One Big Beautiful Bill Act, enacted July 2025) has made the $750,000 limit permanent for post-2017 loans and is expected to reinstate the mortgage insurance premium deduction starting in tax year 2026. Always check IRS.gov/Pub936 or IRS.gov/OBBB for the most current updates before filing future returns.
Frequently Asked Questions About IRS Mortgage Interest Deduction Rules
Can I deduct interest on a second home?
Yes, if it qualifies as your designated second home and meets all other rules.
What if my mortgage exceeds the debt limit?
You can deduct a percentage of the interest equal to (qualified limit ÷ average mortgage balance).
Do I need to itemize to claim this?
Yes — the mortgage interest deduction is an itemized deduction only.
Are there any changes for 2026 tax year?
The debt limit is now permanent, and PMI may become deductible again — verify with updated IRS guidance.
Maximize Your Savings: Consult a Tax Professional
The IRS mortgage interest deduction can significantly lower your tax bill, but the rules are complex and depend on your specific situation. For personalized advice, review IRS Publication 936, Home Mortgage Interest Deduction and Publication 530, Tax Information for Homeowners, or consult a qualified tax professional or CPA. Rules can change, and accurate record-keeping is essential.
Stay informed at IRS.gov and always use the most current forms and publications when preparing your 2025 or future tax returns. This guide is for informational purposes and is not a substitute for professional tax advice.