Deducting Mortgage Interest on Two Homes at Once: The $750K Rule

TL;DR: You can deduct mortgage interest on a main home and one second home, but the IRS caps the deductible loan balance at $750,000 combined for mortgages taken out after December 15, 2017 (or $1 million if the loan predates that date). You also have to itemize on Schedule A, and the second home can't be rented out more than 14 days a year if you want the interest to count.

_Last reviewed: August 2026 · 6 min read_

Owning two homes sounds like double the tax benefit, but the IRS doesn't see it that way. There's one debt ceiling that covers both properties, and if you're not itemizing, none of this matters anyway. Here's how the rule actually works, and where owners commonly get tripped up.

Okoniq Property Hub keeps mortgage statements, closing dates, and loan balances for both properties organized in one place, so you're not digging through old paperwork when tax season hits.

Can you deduct mortgage interest on two homes at once?

Yes, the IRS allows mortgage interest deductions on a primary residence and one additional home, as long as you itemize deductions instead of taking the standard deduction. For 2025, the standard deduction is $14,600 for single filers and $29,200 for married couples filing jointly, so your combined mortgage interest, property taxes, and other itemized items need to clear that bar before the deduction does anything for you.

The "second home" doesn't have to be a beach house or ski cabin. It can be any property you own and use as a residence, including a mobile home, RV, or boat, as long as it has sleeping, cooking, and toilet facilities. What it can't be is a third, fourth, or fifth property. The IRS only recognizes a main home plus one qualified second home for this deduction, no matter how many mortgages you're carrying.

What's the dollar limit across both mortgages combined?

The limit is $750,000 in total mortgage debt across both properties for loans originated after December 15, 2017. That's not $750,000 per house. If you owe $500,000 on your main home and $400,000 on a second home, only $750,000 of that $900,000 combined balance generates deductible interest. The extra $150,000 is excluded.

Married couples filing separately split that cap to $375,000 each. If your loans closed before December 16, 2017, you're grandfathered into the older $1 million limit, which is worth checking closely if you refinanced since then, since a straight rate-and-term refinance usually preserves the grandfathered amount but a cash-out refinance can shrink it. If you're weighing that tradeoff, comparing a HELOC to a cash-out refinance is a good next step before you touch the original loan.

Does the second home have to be a vacation home, or can it be a rental?

It has to function primarily as a personal residence, not a rental property, to qualify for this deduction. The IRS rule is specific: you can rent the home out, but you must personally use it for more than 14 days a year, or more than 10% of the days it's rented at fair market value, whichever is greater. Cross that line and the property gets reclassified as a rental for tax purposes, which shifts the interest deduction to Schedule E instead of Schedule A, with different rules around depreciation and passive activity losses.

This distinction matters more than most owners expect. A cabin you rent out 20 weekends a year but also use yourself for a month easily stays a "second home." A property you rent out 300 days a year and visit twice does not. If you're renting out either property, the insurance requirements change too, and it's worth understanding how landlord insurance differs from homeowners coverage before you start collecting rent checks.

| Second Home (Personal Use) | Rental Property | |---|---| | Interest deducted on Schedule A | Interest deducted on Schedule E | | Must be used 14+ days/year personally | No personal-use minimum required | | Subject to $750K combined debt cap | Not subject to the personal residence cap | | No depreciation deduction | Depreciation deduction allowed |

What if a home equity loan or HELOC is involved instead of a first mortgage?

Interest on a home equity loan or HELOC only counts toward this deduction if the money was used to buy, build, or substantially improve the home securing the loan. This changed under the 2017 tax law. Before that, you could deduct interest on up to $100,000 of home equity debt used for almost anything, including paying off credit cards or funding a business. That blanket allowance is gone through at least 2025.

So a HELOC used to renovate your second home's kitchen still counts toward the $750,000 cap and generates deductible interest. The same HELOC used to pay for a kid's tuition or consolidate debt does not, even if it's secured by the same house. If you're deciding between tapping equity through a loan versus a line of credit, home equity loan versus HELOC breaks down how the structure affects your rate and repayment, which matters here since the tax treatment depends entirely on how you spend the money, not which product you pick.

How do you actually calculate the deductible portion if you're over the limit?

You prorate it. If your combined average mortgage balance across both homes was $900,000 for the year and the cap is $750,000, you can only deduct 83% of the interest you paid (750,000 ÷ 900,000). Most tax software handles this calculation automatically once you enter both Form 1098s, but it's worth checking the math yourself, especially in a year when you refinanced or paid down a balance partway through. Your mortgage statement shows the interest paid for the year, and your loan's amortization schedule can help you estimate your average balance if you're trying to plan ahead rather than wait for the 1098.

FAQ

Can I deduct mortgage interest on a home I'm building but haven't moved into yet?

Yes, interest on a construction loan can qualify if you move into the home within 24 months of when construction begins, and the loan is treated as home acquisition debt for that period.

Does the $750,000 limit apply to the purchase price or the loan balance?

It applies to the loan balance, not the purchase price. A $900,000 home bought with a $200,000 down payment has a $700,000 mortgage, which falls under the cap entirely.

What happens if I sell one of the two homes mid-year?

You can still deduct the interest paid on that home for the months you owned it, and your combined debt limit is calculated based on the balances that existed during the time you held both properties.

Can I switch which property counts as my "second home" from year to year?

Yes, the IRS lets you choose which qualifying property is treated as your second home each tax year, which can be useful if you own more than two residences and want to optimize which one's interest you deduct.

Is mortgage insurance premium interest also deductible on a second home?

Congress has let the mortgage insurance premium deduction lapse and reinstate several times over the past decade, so check current-year IRS guidance before assuming PMI on either property is deductible.

This is educational information, not tax advice. Talk to a CPA about how the mortgage interest deduction applies to your specific loan balances and filing status.