If you pay a mortgage in the U.S., you have probably heard you can "write off the interest." The real rules in 2026 are more specific, and many homeowners either miss the deduction or claim it incorrectly. This guide explains exactly how the mortgage interest deduction works, who qualifies, and how to calculate it.
Summary You can deduct mortgage interest only if you itemize, the loan is secured by your primary or second home, and the debt is within IRS limits. Use the MID Test below to confirm eligibility in under five minutes.
Table of Contents
- Quick Answer: Is Mortgage Interest Deductible in 2026?
- The MID Test: A Simple Eligibility Framework
- Step 1: Itemize or Standard Deduction
- Step 2: Confirm the Loan Qualifies
- Step 3: Apply the Loan Balance Limits
- Refinances, Points, and Prepaid Interest
- HELOCs and Home Equity Loans
- Special Cases: Second Homes, Co-Borrowers, and Rental Use
- Step-by-Step Calculation Example
- Common Mistakes and Audit Triggers
- FAQs
- Updated for 2026: What to Watch
- Change Log
Quick Answer: Is Mortgage Interest Deductible in 2026?
Yes, but only if all three conditions are true:
- You itemize deductions on Schedule A.
- The loan is secured by your primary or second home.
- The debt is within IRS limits and the funds were used to buy, build, or substantially improve the home.
If any condition fails, the interest is not deductible on your federal return.
The MID Test: A Simple Eligibility Framework
Use the MID Test to validate your deduction:
M = Must itemize
I = Interest on qualified home
D = Debt within limits and used for home acquisition or improvements
Step 1: Itemize or Standard Deduction
Mortgage interest appears on Schedule A, which means you must itemize. If your standard deduction is larger than your total itemized deductions, the mortgage interest deduction provides no benefit.
When itemizing makes sense:
- You have sizable mortgage interest
- Your property taxes are close to the SALT cap
- You have additional deductions like charitable gifts or medical expenses
If you are close, compare both options before filing.
Step 2: Confirm the Loan Qualifies
Only qualified home debt counts. That means the loan must be secured by your primary residence or one second home.
Qualified loans include:
- Purchase mortgages
- Construction loans (for building your home)
- Refinance loans (up to the balance of the old loan)
Non-qualified loans include:
- Personal loans secured by the home but used for unrelated expenses
- Investment property loans for homes you do not use as a residence
Step 3: Apply the Loan Balance Limits
Under current law, the mortgage interest deduction is capped based on loan balance:
- Up to $750,000 of qualified debt for most newer mortgages
- Up to $1,000,000 for certain older, grandfathered loans
If your balance exceeds the limit, you can deduct only the portion of interest tied to the capped amount.
Example cap calculation:
If your average mortgage balance is $900,000 and the cap is $750,000, only 83.3 percent of your interest is deductible.
Refinances, Points, and Prepaid Interest
Refinances
You can deduct interest on a refinance only up to the remaining balance of the original loan. Any extra cash-out proceeds are deductible only if used to improve the home.
Points
Mortgage points are prepaid interest. You can typically deduct them in the year paid if the loan is for a primary residence and points are a standard practice in your area. Otherwise, points are deducted over the life of the loan.
Prepaid Interest
Interest paid in advance at closing is deductible in the year it was paid, as long as it is for a qualified home.
HELOCs and Home Equity Loans
Interest on a home equity loan or HELOC is only deductible if the funds were used to buy, build, or substantially improve the home that secures the loan.
Examples:
- Deductible: HELOC used to remodel the kitchen
- Not deductible: HELOC used to pay off credit cards or fund a vacation
This is a common audit trigger, so keep invoices and contractor agreements.
Special Cases: Second Homes, Co-Borrowers, and Rental Use
Second Homes
You can deduct interest on one second home, but only if you use it as a residence. If you rent it out most of the year, different rules apply.
Co-Borrowers
If two people share a mortgage, each can deduct the interest they actually paid. Keep clear records if you split payments.
Mixed-Use or Rental Use
If you rent your home for part of the year, you may need to allocate interest between personal and rental use. Rental use is reported on Schedule E.
Try the tool
Step-by-Step Calculation Example
Scenario:
Maria and Alex buy a home in 2026 with a $650,000 mortgage. They pay $28,000 in interest during the year and $9,500 in property taxes. They also donate $2,000 to charity.
Step 1: Itemize or standard?
Itemized deductions = $28,000 + $9,500 + $2,000 = $39,500.
They itemize because it beats the standard deduction.
Step 2: Qualified debt?
Yes, the loan is secured by their primary residence.
Step 3: Debt limit?
The balance is below the $750,000 limit. All interest is deductible.
Result:
They deduct the full $28,000 of mortgage interest on Schedule A.
Common Mistakes and Audit Triggers
- Claiming interest when you took the standard deduction
- Deducting interest on a loan used for non-home expenses
- Forgetting to prorate interest above the loan balance cap
- Deducting points improperly after a refinance
- Double-counting interest paid by the seller at closing
FAQs
Can I deduct mortgage interest if I rent out the home?
Yes, but interest may need to be allocated between personal use and rental use. The rental portion is generally reported on Schedule E.
Does mortgage interest include PMI?
Mortgage insurance premiums are not currently deductible under federal law. Check for any new extensions before filing.
What if I pay the mortgage but I am not on the deed?
You can generally deduct interest only if you are legally liable for the debt and actually paid it.
Is interest on a construction loan deductible?
Yes, if the loan is used to build your primary or second home and the home becomes a qualified residence within the allowed time period.
Updated for 2026: What to Watch
Mortgage interest rules depend on federal law that can change. For 2026, watch for:
- Possible updates to the $750,000 loan balance cap
- Changes to deductibility of mortgage insurance premiums
- IRS guidance on refinances and home equity interest
Change Log
- 2026-02-06: Initial 2026 version with updated eligibility framework and examples.
Sources: IRS Publication 936, Schedule A instructions, IRS guidance on home equity interest.
