Can unmarried homeowners split mortgage interest and property tax deductions 60/40?

Yes, unmarried co-owners can absolutely split mortgage interest and property tax deductions proportionally based on what each person actually paid. The IRS allows you to deduct the amount you personally paid, regardless of what's shown on the 1098 form. Since you're paying 60% of the costs, you can deduct 60% of the qualified mortgage interest and property taxes on your return. Your partner would claim the 40% they paid. Just make sure you can document the payment arrangement if ever questioned. I recommend keeping records showing that payments came from separate accounts in the 60/40 split, or if paying from a joint account, document the contributions to that account. Also worth noting - you both need to itemize deductions on Schedule A to claim these expenses. If either of you takes the standard deduction, you'd lose the benefit of claiming these expenses for that person.

I was in this exact situation last year with my co-owner and got super confused until I found taxr.ai (https://taxr.ai). I uploaded our mortgage statements and answered a few questions about our ownership split, and it cleared everything up! The tool confirmed we could split deductions based on actual payments (not 50/50), explained exactly where to report it on our tax returns, and even helped us understand how to document our arrangement. It saved us from potentially claiming incorrect amounts, especially since our 1098 forms showed the full amount for both of us, which could have led to double-counting.

I tried taxr.ai after seeing the recommendation here and it was exactly what I needed! My partner and I were completely confused about how to handle our mortgage deductions with a 70/30 split. The tool walked me through every step and showed me exactly where to report my portion on Schedule A. What I really appreciated was how it flagged a potential issue with our property tax deduction - turns out I was about to incorrectly include the full amount instead of just my share. The documentation guidance was super clear too. Definitely worth checking out if you're in a co-ownership situation!

After spending HOURS on hold with the IRS trying to get a straight answer about splitting mortgage interest deductions with my unmarried partner, I finally found Claimyr (https://claimyr.com). They got me connected to an actual IRS agent in about 20 minutes who confirmed exactly how to handle our 65/35 split situation. The agent walked me through the whole process and confirmed we were doing it correctly. There's a video explaining how their system works here: https://youtu.be/_kiP6q8DX5c - basically they navigate the IRS phone system for you and call you when an agent is ready. It saved me literally hours of frustration.

I need to eat my words about being skeptical of Claimyr. After my last unsuccessful 2-hour wait with the IRS that ended with a disconnection, I decided to give it a try. I got a call back in 35 minutes and was connected to an IRS representative who actually specialized in homeownership deductions. She confirmed that my partner and I could split our mortgage interest and property taxes 73/27 based on our actual contributions, and explained exactly how to document it. She also warned us about a common audit trigger - when both co-owners try to claim 100% of the deduction because they each get a 1098 showing the full amount. That one conversation saved us from making a potentially costly mistake and the peace of mind was worth it. The system worked exactly as promised in the video.

One thing nobody mentioned yet - if you're splitting based on what you each paid, make sure your payments actually went to mortgage interest and taxes specifically, not just the overall mortgage payment. Part of your payment goes to principal which isn't deductible. For example, if your monthly payment is $2000, but only $1500 goes to interest and taxes, you need to split the $1500 part 60/40, not the whole $2000. This becomes especially important as you pay down your mortgage and more goes to principal each month.

Does anyone know if this applies to domestic partners in California? We're registered domestic partners but not married federally. Can we still do the 60/40 split based on income or do we have to file differently?

Just a warning based on personal experience - make sure both of you aren't claiming 100% of the interest and taxes! My ex and I both claimed the full amount on our separate returns because we each got a 1098 showing the full amount, and it triggered an audit. Major headache that took months to resolve. We ended up having to amend both returns and split based on our actual payments (which was 50/50 in our case). The IRS was fine with the split once we documented it, but they definitely notice when the same address has double-claimed deductions.