Second Homes and Vacation Rentals: Mortgage Interest and Personal Use

Mortgage interest can qualify on a main home and one qualifying second home, subject to the debt, use, and deduction rules. A vacation home that is also rented requires a closer look at personal-use days and rental days.

Federal references checked October 21, 2026. The IRS publications linked here are the 2025 editions currently available. Match a tax question to its stated year and use the applicable year's guidance for a return.

Jump to: Qualifying homes · The personal-use test · Debt limits · Rental treatment · Practice

Start with the home and the debt

The itemized home-mortgage-interest deduction generally requires a secured debt on a qualified home and itemizing on Schedule A. Loan proceeds and debt limits also matter. Ordinary principal repayments are not deductible mortgage interest. See IRS Topic 505, Interest Expense.

• Main home: generally where you ordinarily live most of the time.
• Second home: one additional home you select that meets the applicable requirements. Owning three homes does not create three personal qualified-home interest allowances.
• Second home not offered for rent or resale: Publication 936 says you do not have to use it during the year for it to qualify as a second home.

A “second home” describes a property's use. A second mortgage describes lien priority. They answer different questions.

If it is rented, apply the personal-use test

For a second home rented during the year, personal use must exceed the greater of 14 days or 10% of the days rented at a fair rental price. Equaling the larger threshold is not enough. This test is explained in IRS Publication 936, Qualified Home.

These examples test only the use threshold. They do not establish that every interest dollar is deductible. Count days using IRS definitions: personal use can include certain family stays and below-market rentals, not just the owner's vacations.

The debt limit applies across the qualifying homes

For ordinary qualifying acquisition debt incurred after December 15, 2017, the general limit is $750,000 of debt, or $375,000 for married filing separately, across the main and second home together. It is not a separate limit for each house and is not a dollar amount of interest you can deduct. Older debt and certain refinancing or transitional situations have different rules.

The proceeds generally must buy, build, or substantially improve the home securing the debt. A loan secured by a home does not automatically qualify when the money pays personal expenses. Use Publication 936's debt categories and worksheet when balances or dates make the calculation more complex.

What if the property is treated as a rental?

Failing the second-home use test does not automatically make every interest expense nondeductible. Qualifying rental interest may instead be considered with rental income and expenses, subject to the applicable allocation and deduction limits. Mixed personal and rental use requires separating the uses; do not deduct the same interest twice. See Publication 527, Residential Rental Property.

There is also a separate rule for a dwelling used as a residence and rented for fewer than 15 days: generally, the rent is not reported as income and expenses are not deducted as rental expenses. Do not confuse those rental days with the personal-use threshold above. IRS Topic 415 explains both rules and the personal-use categories.

Check your understanding

1. A vacation home has 160 fair-rental days and 16 personal-use days. Does it exceed the personal-use threshold?
2. A taxpayer owns a main home and two vacation homes. Can both vacation homes automatically count as qualified second homes for the personal home-interest deduction?
3. Does a property's failure to qualify as a second home rule out examining rental-interest treatment?

Answers and explanations

1. No. The larger threshold is 16 days. Exactly 16 does not exceed it; 17 whole personal-use days would.
2. No. Generally only one is selected as the qualified second home. Publication 936 explains limited changes during the year.
3. No. Rental treatment is a separate analysis of use, expenses, and limitations.

For course study, identify the requested classification before calculating a deduction. For an actual return, a qualified tax professional can apply the year's rules to the taxpayer's complete facts.

Continue with tax depreciation and basis, capital gains, and home-sale exclusions.

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