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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Birthday bill split

1000 replies

KnickerlessFatWoman · 18/07/2026 12:55

Last weekend was my mother’s birthday, so we - that’s me, my parents, sister and BIL and their 12 year-old son - went for Sunday lunch. Unfortunately the food wasn’t great, and they ended up taking my main off the bill.

My dad is someone who always wants to treat everyone, so my sister and I decided this time it was our turn and we were going to treat him and our mum instead. When the bill came, BIL asked if we could split it over two cards, but they said they could only take one payment. He paid and I said I’d transfer my share. For the sake of keeping the maths simple on this thread, let’s say the bill was £210, or £35 per head.

Both BIL and sister are crap at responding to messages, so it took me until midweek to get the bank details. I sent over £70 to cover me and one of my parents.

I heard nothing in response, but I was chatting to my mum earlier and she said “Oh, by the way, Katie said you got the money wrong - it was £210 and you only sent £70”. I said no, that was right - my meal and one other. She said, “Ohhh… I think she thought you were splitting it”. I laughed and said, “No, we said we’d treat you and Dad. I didn’t say I’d pay for three meals!”

I don’t really know why my sister couldn’t just have messaged me instead of talking to our mother about it, but that’s not really the issue. Surely she and BIL don’t expect me to pay half the bill? By treating our parents, I meant exactly that - not that I’d pay for them both while my sister just paid for her own family (which is what this amounts to). There are three of them and one of me. If I pay half the bill, sister and BIL have only covered themselves and their child - there’s no “treating” anyone at all.

AIBU for thinking £70 was my share and paying just that?

OP posts:
Gemilo · 19/07/2026 08:26

I can see where you are coming from. If you had spent £70 on a gift voucher for a meal for them you would have paid £35 each.

KnickerlessFatWoman · 19/07/2026 08:26

dontmalbeconme · 19/07/2026 07:51

In my mind, you parents generally pay the whole bill. You agree to "treat" them, so you split the whole bill that they would have otherwise paid equally. So I'd have expected 50:50.

A few people have argued this. But not one of them has been able to explain why this means I pay more. Surely if us paying rather than them is the treat, that means we pay for ourselves AND them? Not one sibling pays for themselves and pays nothing for their parents?

OP posts:
Shudacudawuda · 19/07/2026 08:26

KnickerlessFatWoman · 19/07/2026 02:09

But why should I pay more? Why can’t my sister and BIL pay for their own meals?

I didn’t say you should did I? Its just a nice thing to do and the way we operate in my family, because we, you know, love each other and like to do nice things for each other. If one of us was too skint to do it, another would step in.
You've said youre not too skint so I don't understand the meanness.

MyOtherProfile · 19/07/2026 08:27

This reply has been deleted

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Fair question.

@Calliopespa dad usually pays for all, which means OP benefits by one free meal, or a sixth of the bill each time and sister benefits by three free meals or half of the bill each time.

KnickerlessFatWoman · 19/07/2026 08:28

Birdsongsinging · 19/07/2026 08:23

I disagree, you have both spent the same amount on your parents treat meal!

But if I pay half, she hasn’t spent anything on it! What are you not getting?

OP posts:
KnickerlessFatWoman · 19/07/2026 08:30

Shudacudawuda · 19/07/2026 08:26

I didn’t say you should did I? Its just a nice thing to do and the way we operate in my family, because we, you know, love each other and like to do nice things for each other. If one of us was too skint to do it, another would step in.
You've said youre not too skint so I don't understand the meanness.

What meanness? Why is it mean to expect someone to actually pay for a meal they’re supposed to be paying for?

OP posts:
MyOtherProfile · 19/07/2026 08:30

KnickerlessFatWoman · 19/07/2026 08:28

But if I pay half, she hasn’t spent anything on it! What are you not getting?

OP I would just leave the thread now. You know it doesn't make sense for you to have paid half because that's you paying all your parents bill, or technically half your bill, half your parents bill and half your sister's family bill.

You did the planned thing, paying half of the treat for your parents.
Explain this to your sister and walk away from this thread.

KnickerlessFatWoman · 19/07/2026 08:30

This reply has been deleted

Message deleted by MNHQ. Here's a link to our Talk Guidelines.

thepariscrimefiles · 19/07/2026 08:33

user1492757084 · 19/07/2026 08:25

I'd have paid 50/50.
Split the bill usually means equally.
The treat was that your parents had a meal with all of their family, including children.

Similar if you had invited your parent's sister and or a child of your far-away brother. If you used the term split the bill and agreed then you signed up for paying half.

You siblings both sound mean spirited. Fancy telling your mother how much the gift of the meal was!! It's terrible that you quibble over small, one off, treats to your parents.

Next time your parents will want to pay for themselves. Your father's generosity has not rubbed off on you. You risk the bond with a sister for 35 pound!

Surely it's OP's sister that is risking the bond with OP? OP agreed to split the cost of their parents' meals between the two of them, so that each of them paid for one parent's food, not to split the whole bill.

I don't understand why people think it's fair that OP, on one income, ends up paying for both parents' meals while her sister in a two income family just pays for herself, her husband and child. OP's sister would end up not treating their parents at all.

Plus, OP's stroppy responses to people who think that she should have split the bill equally have made me laugh so I'm totally on her side.

KnickerlessFatWoman · 19/07/2026 08:34

user1492757084 · 19/07/2026 08:25

I'd have paid 50/50.
Split the bill usually means equally.
The treat was that your parents had a meal with all of their family, including children.

Similar if you had invited your parent's sister and or a child of your far-away brother. If you used the term split the bill and agreed then you signed up for paying half.

You siblings both sound mean spirited. Fancy telling your mother how much the gift of the meal was!! It's terrible that you quibble over small, one off, treats to your parents.

Next time your parents will want to pay for themselves. Your father's generosity has not rubbed off on you. You risk the bond with a sister for 35 pound!

So bloody OTT. “Risk the bond”? We’re hardly going to be daggers drawn forevermore over this.

And yet another poster who can’t explain why I have to be the one who sucks it up. If it’s such a risk to the sibling bond, why can’t my sibling be the one to think “Oh well, it’s only 35 quid”?

OP posts:
Easilyforgotten · 19/07/2026 08:36

Can all the 50/50 people not see that all the arguments saying OP is ungenerous, causing bad feeling, making a fuss over nothing, should suck it up, etc not understand that the exact same arguments apply to the SIL? And more so, because she's the one that has bleated to Mum about this and made her aware there is a 'situation' when there was absolutely no need. Whether SIL misunderstood the intention over the bill or not, the fact remains that she and her family created more of the bill and there are 3 of them to OP's one. She's the one who should have realised OP footing half the bill was unfair and just let it go.
Have you actually spoken to her about this OP? I'm interested in her justification of her position.

Floratheexplorer57 · 19/07/2026 08:38

This is one of those situations where the person who gains doesn't notice that they're gaining and the person who pays for that gain definitely does notice. I would just contact your sister and explain your thinking - I can see both points of view here since she thought the agreement was to split but neither of you really confirmed what you were splitting.

Whether you make more of a fuss about it might depend on all manner of other things e.g. in families often one family will do most of the hosting which is expensive but that can be largely taken for granted - does your sister host more? You know your family set up but I'd check it out with her directly.

Recklessismymiddlename · 19/07/2026 08:38

@Easilyforgotten as I said I’d have paid 50/50 in this situation, but equally, have said the sister should have picked up the phone to the op and not have involved their mum at all. Bad form on her part. I’d not have got my mum involved in any part at all!

Dressfinder · 19/07/2026 08:39

I have 3 kids and my sister has none.
If we took my mother out for a treat meal I would pay for myself, husband and kids and half my mother's meal. My sister would pay for herself, husband and half mother's meal.
It's not a fair split to have one person pay for others when they have agreed to treat an individual.

KnickerlessFatWoman · 19/07/2026 08:40

If you were buying a joint physical gift for your parents with your sister, would you want to only pay a third rather than half if she also wanted to include your BIL’s name on the tag?

No, because I wouldn’t expect him to buy a gift for my parents. But a physical gift isn’t a reasonable comparison here. If we bought a joint gift that cost £200, it would still cost £200 however we split the cost, or if we had a third sibling. The cost of a meal is different, because it depends on how many people attend.

OP posts:
BillieWiper · 19/07/2026 08:41

KnickerlessFatWoman · 19/07/2026 00:53

I said WE should treat our parents. Why does that mean I pay for both?! What is my sister paying?!

Ok so you said she should pay for one of them. Did she agreed? Or misunderstand?

KnickerlessFatWoman · 19/07/2026 08:41

I assume she has misunderstood.

OP posts:
Dressfinder · 19/07/2026 08:43

KnickerlessFatWoman · 19/07/2026 08:40

If you were buying a joint physical gift for your parents with your sister, would you want to only pay a third rather than half if she also wanted to include your BIL’s name on the tag?

No, because I wouldn’t expect him to buy a gift for my parents. But a physical gift isn’t a reasonable comparison here. If we bought a joint gift that cost £200, it would still cost £200 however we split the cost, or if we had a third sibling. The cost of a meal is different, because it depends on how many people attend.

What a stupid comparison.

This would actually be more like if OP and Dsis had agreed to split a gift for mum and then DSis also bought gifts for her husband and children at the same time, would OP pay for half of all the gifts?

OneLimePombear · 19/07/2026 08:44

KnickerlessFatWoman · 19/07/2026 08:41

I assume she has misunderstood.

Have you sent her a clear breakdown down of your calculations with your reasoning behind why you sent £70?

If so leave it at that and try and move on.

user8756 · 19/07/2026 08:46

OP I can see why that is annoying. You sister should have talked to you directly and also not expected you to pay for her husband and son.
Think you have to talk to her and explain your POV which makes total sense, but be prepared in case she doesn't back down and there is more family drama. Some people can be hard to placate and she sounds a bit petty.

burnoutbabe · 19/07/2026 08:46

Easilyforgotten · 19/07/2026 08:36

Can all the 50/50 people not see that all the arguments saying OP is ungenerous, causing bad feeling, making a fuss over nothing, should suck it up, etc not understand that the exact same arguments apply to the SIL? And more so, because she's the one that has bleated to Mum about this and made her aware there is a 'situation' when there was absolutely no need. Whether SIL misunderstood the intention over the bill or not, the fact remains that she and her family created more of the bill and there are 3 of them to OP's one. She's the one who should have realised OP footing half the bill was unfair and just let it go.
Have you actually spoken to her about this OP? I'm interested in her justification of her position.

Yes I can see both arguments. We are explaining how it could be seen that way by the sister to give the other point of view. A misunderstanding of what the treat actually was.

op thinks it’s to pay for the parents meals.
sister though it was to pay for the entire dinner which the parents usually pay for.

the sister is crap for raising it with mum. Everyone agrees that part.

calling everyone thick who can’t understand both points of view isn’t particularly good.

Shudacudawuda · 19/07/2026 08:47

KnickerlessFatWoman · 19/07/2026 08:30

What meanness? Why is it mean to expect someone to actually pay for a meal they’re supposed to be paying for?

Its not mean if you're skint. But if you're out with people you're supposed to love and have enough money for the amount to be inconsequential to you, then in my opinion its mean. And I think lots of people would agree.
Doesn't treating your family because you can give you a nice warm fuzzy feeling? Do you enjoy giving gifts at Christmas? Do you add up how much you spent on them and check they spent the same on your gift so it's 'fair'? If you're that kind of person then yes, youre mean.

Speakeasier · 19/07/2026 08:48

EvangelicalAboutButteredToast · 18/07/2026 13:17

I can see why there was a misunderstanding.

i tnink you are saying that your father usually pays for everyone, so your sisters family usually pay zero. You agreed to ‘split the bill’ and from your sisters point of view that meant half each, I think. I would have thought the same. If what you meant was that you and your sister would cover your parents’ meals then that’s a whole different sentence.

Edited

Really would you? I wouldn’t think the other person would be subsidising MY family. Why should they? The point was that the parents should be treated not the sister’s family.

And it’s very poor form to go whinging to the birthday girl. It just sours the treat for OP’s mum. I’d be very annoyed with my sister to be honest. If she has a problem she should have come to you about it.

Bookbears · 19/07/2026 08:49

@KnickerlessFatWoman much did your actual bill come too? If you weren’t going to split the bill and just paid for exactly what you had (with your main meal taken off), what would it come to for you personally? And then what would it have been for your non drinking BIL?

I agree with what you have paid and your reasoning for it. I’m just wondering if your sister has got her knickers in a twist because your meal was a lot more expensive due to alcohol? Although unlikely if your main meal was taken off the bill.

ie, for ease of this explanation. Say the total bill was £240 for 6 people which equates to £40 each if split equally, but out of that £240 you had a £30 bottle of wine on top of your meal and no one else did. Your ‘share of the bill’ would have actually been £70, not £40, leaving everyone else’s share as £34 each.

You said to split the bill and pay for parents so she is expecting you to have paid the £70 you owed, plus £34 for your mum - making it £104 from you, and they pay the rest which is £34 x 4 people (BIL, sis, nephew and dad)?

God I hate going out for meals that aren’t just my husband and kids. It becomes so stressful trying to split and bill, everyone always has different ideas on how it works. It always amazes me at the logic some people use to get to their calculations - normally so they end up paying less than everyone else!

I will never forget the time I went out for a meal for someone’s birthday and the waitress forgot to put through one of meals, apologised profusely when she realised, cooked the meal and took it off the bill, gave us all a free round of drinks and free sharing dessert. The person whose meal was free still tried to say she should pay anything for her meal as she had to eat her main by herself - wanted the rest of us to pay for her starter, alcohol and the other dessert she wanted 🙄. Then they gave us 6 bag of sweets at the end (something the restaurant always does) as there were 6 people at the table and she took all 6 bags home 🤣. Still can’t believe it to this day.

Speakeasier · 19/07/2026 08:51

Shudacudawuda · 19/07/2026 08:47

Its not mean if you're skint. But if you're out with people you're supposed to love and have enough money for the amount to be inconsequential to you, then in my opinion its mean. And I think lots of people would agree.
Doesn't treating your family because you can give you a nice warm fuzzy feeling? Do you enjoy giving gifts at Christmas? Do you add up how much you spent on them and check they spent the same on your gift so it's 'fair'? If you're that kind of person then yes, youre mean.

It’s fine to treat someone if you’ve chosen to. But the OP didn’t. She just chose to treat her parents, shared with her sister’s family. And that’s fine.

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