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Home Mortgage Interest Deductions

The mortgage interest deduction is one of the most valuable tax benefits of homeownership, but which interest actually qualifies depends on how and where the debt is secured.

Deductibility, in general

Home mortgage interest is interest paid on a loan secured by your main home or a second home, whether that's a purchase mortgage, a second mortgage, a line of credit, or a home equity loan. You can only claim it as an itemized deduction if you're legally liable for the debt and there's a genuine debtor-creditor relationship with the lender; paying someone else's mortgage doesn't qualify. The loan also has to meet two additional tests: it must be a secured debt, and it must be secured by a qualified home, both explained below.

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When is interest fully deductible

Whether all of your mortgage interest is deductible depends on when you took out the loan, how much you borrowed, and what you used the proceeds for. Interest is generally fully deductible if every mortgage you hold falls into one of three categories throughout the year: debt taken out on or before October 13, 1987 (grandfathered debt); acquisition debt taken out after that date to buy, build, or improve your home, currently capped at $750,000 of combined principal for married filers ($375,000 married filing separately) through 2025, with a $1 million grandfathered limit for loans that predate the Tax Cuts and Jobs Act of 2017; or home equity debt other than acquisition debt, capped at $100,000 ($50,000 married filing separately) and further limited by your home's fair market value. Under current law, the loan generally has to be used to buy, build, or substantially improve the home securing it in order to qualify.

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What is secured debt

Your mortgage only qualifies if it's a secured debt, meaning you've signed an instrument, such as a mortgage or deed of trust, that puts your home up as collateral, allows the lender to use the home to satisfy the debt in a default, and is properly recorded under applicable state or local law. A debt secured only by a general lien on your assets, or one attached without your consent (like a mechanic's or judgment lien), doesn't count, and neither does an unrecorded wraparound mortgage.

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What is a qualified home

A qualified home is your main home or one second home, which can be a house, condo, co-op, mobile home, house trailer, or boat, as long as it has sleeping, cooking, and toilet facilities. You can only have one main home at a time. A second home you don't rent out can be treated as qualified without any minimum personal use requirement, but a second home you do rent out must also be used personally for more than 14 days, or more than 10 percent of the days it's rented at fair value, whichever is longer, or it's treated as rental property instead. If you own more than one second home, only one can be treated as qualified in a given year, though you can switch which one under certain circumstances, such as buying a new home or selling the existing second home.

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Hybrid situations

Only the portion of your home used for residential living counts as a qualified home. If part of the property is used for something else, most commonly a home office, you'll need to allocate the cost and value between the qualifying and non-qualifying portions, which can reduce your deduction. Renting out part of your home doesn't disqualify it as long as the rented space is used by the tenant primarily as a residence, isn't a fully self-contained unit, and you don't rent to more than two tenants at once. A home office used in your business may separately qualify you for business-use deductions, including on the business portion of your mortgage interest.

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Married taxpayers

Married couples filing jointly can treat a qualified home as jointly or individually owned. Those filing separately can each claim only one home as qualified, unless both spouses agree in writing to let one spouse claim both a main and second home. If a divorce or separation agreement requires paying mortgage interest on a jointly owned home, that payment may be treated as alimony rather than a straightforward interest deduction.

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Special rules

A few less obvious situations affect this deduction. Late payment charges and prepayment penalties generally count as deductible mortgage interest, as long as they aren't fees for a specific service. If you sell your home, you can deduct interest paid up through, but not including, the date of sale. Prepaid interest generally must be spread across the tax years it applies to, with an exception for points. If you receive a mortgage interest credit through a state or local mortgage credit certificate, you must reduce your interest deduction by the credit amount. And rent paid before a purchase officially closes is not deductible as interest, regardless of what the settlement paperwork calls it.

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Form 1098

If you paid $600 or more in mortgage interest during the year, your lender will typically send you IRS Form 1098, the Mortgage Interest Statement, by January 31 of the following year, with a copy also going to the IRS.

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Frequently asked questions

Is all mortgage interest tax deductible?

Not automatically. It depends on when the loan originated, how much you borrowed relative to current limits, and whether the debt is properly secured by a qualified home.

Can I deduct interest on a home equity loan?

Often, but it's now limited to debt used to buy, build, or substantially improve the home securing the loan, subject to the combined acquisition-debt caps described above.

What happens to my mortgage interest deduction if I use part of my home for business?

You'll generally need to allocate the mortgage interest between the residential and business-use portions of the home, which can reduce the itemized deduction while potentially qualifying you for separate home-office business deductions.

This guide is for general informational purposes only and is not tax, legal, financial, or investment advice. Every business situation is different, so consult a licensed professional before making decisions based on this content.