How to Split Mortgage Interest Tax Deductions

Co-owners each claim the share of the interest they paid.

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Every year, your mortgage lender sends you a Form 1098 showing how much mortgage interest and mortgage insurance premiums you paid. If you split the mortgage with a friend, sibling, parent or partner, you still only get one Mortgage Interest Statement. Unless you made 100 percent of the payments, you don't get to claim 100 percent of the tax write-off. The mortgage interest tax deduction will need to be divided between you and the other homeowner on the deed.


If you split a mortgage with someone, the interest tax deductions are split according to what percent each person split the payments at.

Mortgage Interest Write-Off Explained

You only get a tax deduction for mortgage interest you've personally paid. If, say, your co-owner pays 75 percent of the mortgage each month and you pay 25 percent, you can claim 25 percent of the interest and premiums reported on the 1098.

If your partner, say, got the 1098 instead of you, sit down and figure out how much of the interest each of you can deduct. Report your share on Schedule A. Attach a statement explaining why the lender didn't send the IRS a 1098 with your name on it and how much interest you and your co-owner paid. Your co-owner simply subtracts out your share of the payments and reports her own contribution. She doesn't send in a 1098 – that's the lender's job.

If you make three times what your co-owner does, you may need the extra tax deduction a lot more than him. You can't deduct more mortgage interest than you paid, even if you need the write-off. Instead, consider taxes when you're figuring out who will be responsible for specific household expenses. If you know you want a big deduction, you can pay most (or all) of the monthly mortgage payment. Your co-owner can make up for your taking on this expense in whatever way both of you agree is fair.

Exceptions to Shared Home Deductions

If, say, you're helping your daughter out financially with her house payments but you aren't the co-owner of the home or legally responsible for the debt, you're out of luck at tax time. With no ownership stake in the house, you have no claim to the mortgage interest write-off.

If you co-own a home with your spouse and file separate income tax returns, you follow the same procedures listed above. The exception applies if you live in a community property state. In that case, you split everything right down the middle, with each of you reporting half your community income and half your community expenses. Deductions from income work the same way – if the house is community property, you each get 50 percent of the write-off, regardless who who made the mortgage payments. Use Form 8958 (Allocation of Amounts Between Certain Individuals in Community Property States) to determine how the income and expenses will be divided for income tax purposes.

Mortgage Interest Deduction for 2019

As a result of the Tax Cuts and Jobs Act (TCJA), the home mortgage interest deduction follows 2018 figures until the TCJA expires in 2025. Pending a cost-of-living increase, this amount may change for 2019.

Mortgage Interest Write-Off for 2018

Under new changes to tax law because of the TCJA, the mortgage interest deduction will only apply to loans of up to $750,000.00 (for married taxpayers filing a joint return), which is reduced from $1 million for tax year 2017. Interest on home equity loans is only deductible if the funds you borrow are used to buy, build or significantly improve your primary home or IRS-qualified second home.

If you have any questions or concerns about shared home deductions, consult an experienced tax professional for personalized help and advice.