How to split home mortgage interest when both names are on mortgage - filing jointly or separately?

My girlfriend and I purchased a house in early 2024 and we're both names on the mortgage. Now we're trying to figure out the smartest tax strategy for the upcoming tax season. We're leaning toward filing separately because she earns significantly more than me and could potentially benefit from itemizing deductions while I just take the standard deduction. Here's where I'm confused - if we divide the mortgage interest between us, I think we'd both end up having to take the standard deduction. But if she claims ALL the mortgage interest, she could itemize her deductions while I still use the standard deduction. Is this second approach legal and the most tax-efficient? For what it's worth, she actually pays the full mortgage from her account, and I transfer my portion to her each month. Does the IRS require mortgage interest to be split equally between all names on the mortgage? Or can one person claim it all if they're technically making the payments?

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19 comments

Diego Rojas

•8M

This is a common question for couples with shared mortgages! The general rule is that mortgage interest should be allocated based on who actually paid it, not necessarily based on whose names are on the mortgage. Since your girlfriend pays the full mortgage from her account (even though you reimburse her your portion), she could potentially claim the full mortgage interest deduction. This is because the person who makes the payment to the lender is generally considered the one who "paid" the interest from the IRS perspective. But there's more to consider! Filing separately often results in higher total taxes compared to filing jointly for most couples. The standard deduction for married filing separately in 2025 is projected to be about half of the married filing jointly amount. Plus, many credits and deductions are reduced or eliminated when filing separately.

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Diego Rojas

•8M

You're absolutely right - I misread that part! Since they're not married, they would each file as single taxpayers, not married filing separately. This actually changes the analysis significantly. As unmarried individuals, they each get the full single filer standard deduction. In this case, having one person claim all the mortgage interest might indeed be more beneficial if it pushes that person over their standard deduction threshold. Since the girlfriend is making the actual payments to the mortgage company and the OP is reimbursing her personally, the girlfriend could potentially claim all the interest.

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Sean O'Donnell

•8M

I was in a similar situation last year and was totally confused about how to handle it! I ended up using taxr.ai (https://taxr.ai) which was super helpful for this exact mortgage interest allocation problem. I uploaded my mortgage interest statement and answered a few questions about my payment arrangement with my partner. The system analyzed who could legally claim what portion based on our payment structure, and showed me exactly how to maximize our combined tax benefit. It walked me through several filing scenarios to show which approach would save us the most money overall.

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Sean O'Donnell

•8M

It actually gave me specific advice based on our payment arrangement! It asked questions about who was making payments to whom, amounts, and even our income levels to determine the best filing approach. Much more personalized than the generic calculators I tried before. As for comparing to TurboTax or H&R Block, those are great for filing but not as good at pre-filing strategy. I actually used the recommendations from taxr.ai first to figure out our optimal approach, then used TurboTax to actually file. Saved us around $1,400 combined by optimizing who claimed what.

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Zara Ahmed

•8M

Just wanted to follow up! I decided to try taxr.ai last week after seeing this thread, and it was exactly what I needed. My partner and I uploaded our mortgage docs and answered questions about our arrangement. The analysis showed us that having her claim the mortgage interest (since she makes payments from her account) while I take the standard deduction would save us about $1,200 combined vs. splitting it. It also provided documentation explaining exactly how this approach aligns with IRS guidelines in case we ever get questioned. Super relieved to have a clear answer backed by the actual tax code!

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Luca Esposito

•8M

If you're having trouble getting a clear answer on this, try Claimyr (https://claimyr.com). I called the IRS 3 times about this exact issue last year and couldn't get through. Then I used Claimyr, and they got me connected to an IRS agent in about 15 minutes. You can see how it works here: https://youtu.be/_kiP6q8DX5c The agent confirmed that when unmarried people share a mortgage, the mortgage interest can be claimed by whoever actually pays it. Since your girlfriend pays the full amount (even though you reimburse her), she can technically claim all the interest. The agent also checked our specific situation and confirmed this was legit.

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Luca Esposito

•8M

They use a system that automatically dials and navigates the IRS phone tree until a line opens up, then they call you and connect you. It's not just "keeping calling" - it's more sophisticated and saves you from having to sit on hold. I was skeptical too! I thought it was going to be a waste of time, but I was desperate after trying for days. They called me back in about 15 minutes with an actual IRS agent on the line. The time savings alone was worth it - I didn't have to waste hours on hold. Plus getting an official answer directly from the IRS gave me peace of mind that I wasn't going to get in trouble for how we filed.

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StarStrider

•8M

OK I'm eating crow here and wanted to update. After being skeptical in my earlier comments, I actually tried Claimyr because I've been trying to resolve an issue with my mortgage interest deduction for weeks and couldn't get through to the IRS. Got connected in about 20 minutes (not quite 15, but close enough) and spoke with an agent who confirmed that for unmarried couples, mortgage interest can be claimed by the person making the actual payment to the mortgage company. The agent even emailed me documentation about this rule so I have it in writing. I'll definitely be using this service again next time I need to speak with the IRS. Sorry for doubting!

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Mateo Rodriguez

•8M

Tax preparer here. Just want to point out something that hasn't been mentioned yet. If you're both on the mortgage and both on the deed, you are both technically paying the mortgage interest even if the payment comes from one account. The 1098 will be issued with both names. The IRS could potentially question if one person claims 100% of the mortgage interest when both names are on the form. Not saying they will, but they could. The safest approach is to split it based on economic reality - if you're paying 40% of the mortgage, claim 40% of the interest.

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Mateo Rodriguez

•8M

Yes, that actually does matter. In this scenario, from the mortgage company's perspective, your girlfriend is making 100% of the payments. The 1098 form will likely have both your names on it, but the fact that she's the one physically making the payments gives more weight to her claiming the full interest amount. The IRS generally looks at economic reality - who's actually paying what. Your transfers to her are considered private transactions between you two, not direct mortgage payments. So her claiming the full interest while you take the standard deduction is likely fine, especially if she's paying more than 50% of the household expenses anyway.

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Ethan Taylor

•7d

Another option to consider is consulting with a tax professional who specializes in these situations. I know it costs money upfront, but given the complexity of your situation and the potential tax savings, it might be worth the investment. A CPA can review your specific financial arrangement and provide written documentation of their recommendation. This gives you professional backing if the IRS ever questions your filing approach. They can also run the numbers on multiple scenarios (splitting 50/50, one person claiming all, etc.) to show you exactly which saves the most money. I learned this the hard way - tried to figure it out myself for two years and missed out on significant savings. Finally paid for a consultation and discovered I'd been leaving money on the table. The consultation fee paid for itself in the first year through better tax planning.

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