How Mortgage Interest Deductions Work for a Second Home or Rental Property

When you already have a mortgage on your primary home and you’re thinking about buying another property—maybe a vacation cabin, a condo in a warmer climate, or a rental house to bring in extra income—you probably wonder if the mortgage interest on that second loan will save you money at tax time. The short answer is yes, but the rules are different depending on whether you use the property yourself or rent it out. Let’s walk through the basics so you know what to expect before you sign on the dotted line.

First, remember how the mortgage interest deduction works on your main home. If you itemize your deductions on your federal tax return, the interest you pay on the first $750,000 of mortgage debt (for married couples filing jointly; $375,000 if married filing separately) used to buy, build, or substantially improve your home is deductible. The same general rule applies to a second home, with a catch: the $750,000 limit is a combined limit for both your main home and your second home. So if you already have a $500,000 mortgage on your primary residence, you can only deduct the interest on up to $250,000 of mortgage debt on the second home. That’s important to keep in mind because any interest on debt above that combined cap won’t be deductible.

Now, what counts as a “second home” for tax purposes? The IRS says the property must be one that you personally use for at least 14 days out of the year, or 10 percent of the days you rent it out, whichever is greater. You can’t just call any rental property a second home and deduct all the mortgage interest. If you don’t meet that personal-use threshold, the IRS treats the property as a rental real estate investment instead, which has its own set of rules.

Let’s talk about the rental scenario. When you buy a property specifically to rent out to tenants, the mortgage interest gets treated differently. In that case, the interest is considered a rental expense. You don’t claim it as an itemized deduction on Schedule A the way you do for a primary home or second home. Instead, you report your rental income and expenses—including the mortgage interest—on Schedule E. The beauty of renting is that you can deduct the interest even if it exceeds the $750,000 limit for personal residences, because rental properties have no such cap. You can deduct all the interest on the mortgage as long as the loan is used to purchase or improve the rental property. That can be a huge tax advantage if you’re buying a more expensive rental.

But there’s a twist. If you rent the property out for part of the year and also use it yourself (think of a beach house you rent to strangers for three months and visit yourself for two weeks), the IRS makes you split the expenses between personal and rental use. You’ll need to figure out what percentage of the year the property was rented at a fair market rate, and then you can deduct that same percentage of the mortgage interest and other costs. The personal-use portion of the interest can be claimed as an itemized deduction on Schedule A, but only up to the combined $750,000 limit we talked about. That’s a bookkeeping headache, but it’s manageable with good records.

One more thing to watch out for is the alternative minimum tax, or AMT. If you’re in a higher income bracket, the AMT can disallow or reduce the mortgage interest deduction for your second home. The AMT rules are complicated, but basically, the deduction for interest on a second home mortgage is not allowed under AMT. That means you might lose the tax benefit if your income pushes you into AMT territory. It’s not common for the average homeowner, but worth checking with a tax professional if you earn a lot or have other large deductions.

What about using a home equity loan on your first home to buy a second property? If you take out a home equity loan or line of credit on your primary residence and use the cash to buy a second home, the interest on that loan is deductible as mortgage interest on your primary home, subject to the same $750,000 limit. But here’s the key rule from the Tax Cuts and Jobs Act: the loan must be used to buy, build, or substantially improve the home that secures the loan. If you use a home equity loan from your primary home to buy a vacation house, the IRS says that’s not “substantially improving” your primary home—you’re using the money for a different property. So the interest on that home equity loan may not be deductible at all. The IRS clarified this in 2018, and many taxpayers got caught off guard. So be careful: the deduction depends on what you do with the borrowed money, not where you borrowed it.

Finally, for landlords: if you take out a mortgage on a rental property, the interest is fully deductible as a rental expense, no matter how you use the loan proceeds. You could even use a cash-out refinance on a rental property to buy another rental, and all that interest stays deductible. That’s one reason real estate investors often prefer to use debt to expand their portfolios.

The bottom line is that mortgage interest deductions on subsequent properties can be valuable, but the rules shift based on how you use the property and how much total debt you carry. If you’re buying a second home for your own enjoyment, keep your combined mortgage debt under $750,000 to get the full benefit. If you’re buying a rental, you have more flexibility, but you need to track personal vs. rental use carefully. And always talk to a tax professional before making big decisions—everyone’s situation is a little different, and the IRS has a way of turning simple ideas into complex calculations.