30-year-old sibling buys house with 28-year-old sister, demands to split mortgage into three when sister's husband moves in, they refuse: ‘He is not an equity holder’

Author image for Bar Mor Hazut
Bar Mor Hazut • Senior Editor
Mar 26, 2026 3:00 PM EDT

Some people find themselves in unique living situations… and they have no idea how to manage them without some advice.

Which is exactly why the 30-year-old woman in the story below decided to see what others think of her living situation, and how she might make it better for her family.

These two sisters decided to buy a house together and share every expense. From the mortgage to the bills, everything was evenly split 50/50, and for years, this arrangement worked out just fine. That was until the younger sister got married, and her husband moved into the house with the two siblings. Now, three people lived in the house, and the 50/50 arrangement started to feel off to the older sister. She saw the husband as another occupant of the house, and felt like it was unfair that she pays for half of all the expenses when they should split everything three ways.

For a while, the couple agreed, and every single resident paid for a third of everything, including the mortgage. But at some point, the couple started to demand to go back to the 50/50 arrangement, feeling like it's not right for the husband to pay for a mortgage while his name is not on the house. This led to the two sisters having quite a dispute, as neither of them could agree on an arrangement that felt fair for their living situation.

Since one doesn't hear a lot about two siblings sharing ownership of a house and living in it while one of them is married, there is no simple solution to this situation. Yet, since these sisters clearly care about each other and want to make things right, they are both willing to find a way to keep living together without feeling like one is taking advantage of the other.

Question is, is there a way for them to do that?

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  • Happy first time homeowner holding house keys.
    via georgeclerk

    Happy first time homeowner holding house keys.

    Image is representative only and does not depict the actual subjects of the story.

  • AITA for refusing to pay 50% of the mortgage when three people live in the house?

    I (30f) and my sister (28f) bought a house together. We were going 50/50 on paying the bills, it was fine, but since then my sister has gotten married and her husband has moved in.
    via Gracaphanie
  • That actually didnt cause many problems, since we now were all only paying 1/3 of the bills.
    via Gracaphanie
  • However, my sister and her husband have recently gotten a joint bank account, and my sister now thinks that means we should go back to 50/50.
    via Gracaphanie
  • I disagree, because there's still three people living here. By my calculations, if we did that, I would be paying 50% and they would both be paying 25%.
    via Gracaphanie
  • Meaning I would be paying most of the household bills. I keep trying to explain to her how unfair that is to me, but she keeps insisting that it's unfair to them because the way she sees it, THEY are paying the majority of the bills.
    via Gracaphanie
  • Which I agree is the case, but that's because they're TWO people, and I am ONE person.
    via Gracaphanie
  • But it doesn't matter how many times I try to explain that to her, she just keeps saying that it isn't fair that they are paying more than me.
    via Gracaphanie
  • I will say that this is the first property I've owned, and I don't have any experience with marriage, so maybe it does change something??
    via Gracaphanie
  • But I genuinely feel like I would be getting sc ed over if we go back to 50/50.
    via Gracaphanie
  • I would really appreciate some outside feedback on this, I'm really stressed out by this argument.
    via Gracaphanie
  • AITA? EDIT: Yeah I do actually see how I'm in the wrong here. My sister never mentioned that the house is only in our names so we'd be the only ones getting equity, the argument was always that because they have one bank account it should just count as one person, and that frustrated me because that's not a good argument.
    via Gracaphanie
  • And her husband has never once gotten involved in the discussion, so idk if he feels SC ed over or not.
    via Gracaphanie
  • Smiling Couple Holding Brown Boxes
    via Ivan S

    Smiling Couple Holding Brown Boxes.

    Image is representative only and does not depict the actual subjects of the story.

  • I do think he should contribute because he is using water/oil, but yeah the mortgage should be strictly on us.
    via Gracaphanie
  • We'll have to figure something out. Thanks everyone!! EDIT 2: Okay so we came to an agreement.
    via Gracaphanie
  • One detail I didn't mention before (because it didn't seem relevant but I'm seeing people mention my sister's husband taking up space so it definitely is) is that when my sister and I moved in, we made an agreement that she gets the bigger bedroom and I get the smaller bedroom. and the office.
    via Gracaphanie
  • But then when her husband moved in, all of his stuff got put in my office.
    via Gracaphanie
  • Which has always annoyed me because it felt like my sister was going back on our agreement by essentially giving the space to her husband.
    via Gracaphanie
  • So we talked it all over, and the agreement we have is that my sister and I pay the mortgage 50/50, we split all household costs 3 ways, and her husband pays a little bit of rent.
    via Gracaphanie
  • Partially for wear and tear, but also for the office. (Apparently he has a storage unit already that's full and is unwilling to get a second one.
    via Gracaphanie
  • Which I do understand so this is fine for now). Idk the exact breakdown but maybe it's 60/40?
    via Gracaphanie
  • Again, very grateful for the replies, I am well aware my living situation is stupid haha.
    via Gracaphanie
  • Blue_Letter_Bible One and done. OP you should be paying 50% because you own 50% of the house. If your sister paid 33% and your BIL paid 33% that would mean they should own 66% of the house and you only own 33% of the house. Unless youre willing to forgo 16% of your share... that's yours to pay. This is a good lesson why you shouldnt buy property with someone who isnt your spouse. EDIT: As I said in a later post the BIL should be paying rent and utilities but not 33% of the mortgage.
    via Blue_Letter_Bible
  • Gracaphanie Original Poster's Reply Yeah... my sister and I were pretty desperate to get out of our mom's house and we both had a lot saved up so it seemed like a good idea at the time. And literally everyone in our family thought it was cool af we were doing it. Now six years later I realize I'm in a pretty bad spot. They're gonna want their own house at some point, and I'm going to either have to buy out her half and then rent out the empty room, or we sell. I can't afford to buy her out and e
    via Gracaphanie
  • superjudy 1 Info: do you own half of the house? If so why wouldn't you pay half of the mortgage?
    via superjudy1
  • Gracaphanie Original Poster's Reply Yeah. That is a good point, I wasn't really thinking of it like that. It's not like he'd be getting anything when we eventually sold. We just always split it three ways and equity never came up in the discussion at all.
    via Gracaphanie
  • Virtual-Squirrel-725 You and your sister pay half the mortgage, he pays rent and you and your sister receive half each, and you split the bills 1/3 each. He is not an equity holder so he doesn't pay the mortgage, but he does live there so he pays rent and bills. I'll do rough calculations for you. If the house is worth $500,000, your mortgage payments will be about $2,700 a month. Rent is about 5% of the $500,000 per year, so about $700 a month for him. You and your sister are out of pocket $2,1
    via Virtual-Squirrel-725
  • PassengerForsaken 793 If you're in the UK, anyone who contributes directly to a mortgage has an equitable claim in a property, even if they dont legally own it. Pay your 50% of the mortgage with your sister and then split the rest of the bills 33% each. Dont let someone whose name isn't on the title deed EVER contribute to your mortgage.
    via PassengerForsaken793
  • Dittoheadforever The way I see it, you and your sister should be going 50/50 on the mortgage and utilities should be 1/3 per person. You could also make the argument that he should be kicking in something extra to cover rent for himself, but good luck coming to an agreement on that.
    via Dittoheadforever
  • sab222 Are you getting half the equity? Owning half a house with a couple sounds like a terrible idea
    via sab222
  • ConflictGullible392 Feels like it's fair for them to pay a bit less than 2/3 because a) they presumably share one bedroom while you occupy your own bedroom and more importantly b) you and your sister share ownership of the house 50-50, while the husband does not have any equity. But at the same time feels fair for them to pay a bit more than half because of the presence of a third person, especially when it comes to utilities. Maybe split the difference, you pay 40% they pay 60% between them? Or
    via ConflictGullible392
  • CaterpillarLoud8071 Only owners pay the mortgage, maintenance and renovations, and split it equally. Non owners pay rent, which can be agreed on based on market rent. All occupants pay 1/3 of the bills.
    via CaterpillarLoud8071
  • ShortManBigEggplant NTA but not a smart move on your behalf. You should still pay 50% of the mortgage so you own half the house but he should be paying you both rent.
    via ShortManBigEggplant

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house siblings homeowner new homeowners husband rent mortgage bills family sister brother in law
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