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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:
Clavinova · 19/07/2026 21:50

ThisJollyLemonMoose · 19/07/2026 21:44

@Clavinova you're assuming husband and wife with 12yo child have separate finances (unlikely).

Yes - I have separate finances from my dh. Even if we had joint finances, if I were treating my parents, I think I would make a point of paying.

Empress13 · 19/07/2026 21:51

The misunderstanding was let’s split the bill which usually means going 50/50 so I can see where your sis was coming from but agree it’s not fair to split when there’s only one of you

RabbitlessMagician · 19/07/2026 21:53

Clavinova · 19/07/2026 21:50

Yes - I have separate finances from my dh. Even if we had joint finances, if I were treating my parents, I think I would make a point of paying.

It seems unlikely the sister and BIL have this arrangement - otherwise why did he make a move to pay?

EstoyRobandoSuCasa · 19/07/2026 21:53

Clavinova · 19/07/2026 21:42

As an aside - who hosts Christmas?

You tell me! OP hasn't mentioned this as far as I can see.

ThisJollyLemonMoose · 19/07/2026 21:53

Clavinova · 19/07/2026 21:50

Yes - I have separate finances from my dh. Even if we had joint finances, if I were treating my parents, I think I would make a point of paying.

Even if your husband had benefitted from your parents generosity in the past?

Thirteenblackcats · 19/07/2026 21:55

Haven’t read the full thread but I don’t think you’re being unreasonable.

the agreement was to treat your parents between you, you shouldn’t have to subsidise your sister and her family.

bittertwisted · 19/07/2026 21:58

nobody is ever going to agree on this thread
I would have paid half, any other option would be alien, I am paying half for the group experience for my parents
other people feel different

I will say none of you should ever accept the dad’s generosity again if paying per consumption is so important

Clavinova · 19/07/2026 21:58

ThisJollyLemonMoose · 19/07/2026 21:53

Even if your husband had benefitted from your parents generosity in the past?

Yes, otherwise it wouldn't seem like my gift to celebrate my mother's birthday. I have no problem with dh paying on other occasions.

Perplexed20 · 19/07/2026 21:58

Clavinova · 19/07/2026 21:50

Yes - I have separate finances from my dh. Even if we had joint finances, if I were treating my parents, I think I would make a point of paying.

Separate finances..

So one sister pays for self and one parent = £70

Other sister (wife) pays for self and one parent and 1/2 child.= £70 + (35/2)= 87.50

Brother in law pays for self plus 1/2 child = £52.50

Op still pays £70.
Bil and sister total contribution = £87.50 + £52..50 = £105

Or are you saying sister shouldn't pay anything towards treat at all?

Perplexed20 · 19/07/2026 22:04

bittertwisted · 19/07/2026 21:58

nobody is ever going to agree on this thread
I would have paid half, any other option would be alien, I am paying half for the group experience for my parents
other people feel different

I will say none of you should ever accept the dad’s generosity again if paying per consumption is so important

The thing is single people often end up paying more, and why should they? They have one income and would likely end up either subsidising a double income household or other people's choices. Why should they? And why assume they can afford to.

I went out to dinner with my 3 sisters last week and my 2 young adults (students)., so 6 of us. I paid for 3 meals they pay one each. Why should they pay for us? The Ops case is no different.

Bellyblueboy · 19/07/2026 22:13

Perplexed20 · 19/07/2026 22:04

The thing is single people often end up paying more, and why should they? They have one income and would likely end up either subsidising a double income household or other people's choices. Why should they? And why assume they can afford to.

I went out to dinner with my 3 sisters last week and my 2 young adults (students)., so 6 of us. I paid for 3 meals they pay one each. Why should they pay for us? The Ops case is no different.

Edited

I remember going on holiday many many years ago with my friend and her boyfriend.

we rented a car and they assumed I would pay half (and I did!). Three adults but beciase they were a couple they assumed they counted as one. We stayed in a few triple hotel rooms and again they charged me half. Half for the grocery shop before we went camping (even though the boyfriend ate more than both of us combined!).

I look back and am horrified at what a doormat I was and how cheap they were .

turns out a lot of people are cheap and expect single people to pay more than their share!

Newbie8918 · 19/07/2026 22:29

AgedPudding · 19/07/2026 14:55

sorry disagree, the post said the mum and dad often treat the family (to the family meal) so they (the sisters) decided to treat them instead (to the family meal). That implies 50% each

I agree that makes sense. An 'event' which includes all the immediate family is usually paid for by mum and dad. This time the daughters decide that they will split 'the family event' therefore I would assume 50/50. It's not really to do with who had what. I understand the maths.

I agree but apparently I’m bonkers! I see this as covering dad’s usual debt and this should be 50:50 rather than ‘who has what’. This should have been discussed before obviously!

Perplexed20 · 19/07/2026 22:30

Perplexed20 · 19/07/2026 21:58

Separate finances..

So one sister pays for self and one parent = £70

Other sister (wife) pays for self and one parent and 1/2 child.= £70 + (35/2)= 87.50

Brother in law pays for self plus 1/2 child = £52.50

Op still pays £70.
Bil and sister total contribution = £87.50 + £52..50 = £105

Or are you saying sister shouldn't pay anything towards treat at all?

Correction to maths...

Op = £70.

Sister and brother in law = £87.50 + 52.50 = £140

Perplexed20 · 19/07/2026 22:31

Newbie8918 · 19/07/2026 22:29

I agree but apparently I’m bonkers! I see this as covering dad’s usual debt and this should be 50:50 rather than ‘who has what’. This should have been discussed before obviously!

But why?
Why should single op pay for sister's family?

Say lunch was parent plus sister and brother in law and their 8 children Would op still pay 1/2 then?

Bellyblueboy · 19/07/2026 22:45

Newbie8918 · 19/07/2026 22:29

I agree but apparently I’m bonkers! I see this as covering dad’s usual debt and this should be 50:50 rather than ‘who has what’. This should have been discussed before obviously!

Or, married sister benefits a lot more from dad’s generosity - her husband also gets a free meal, and her child. She costs three times as much as her sister.

When they return the favour they are buying their parents dinner. Sister usually gets three times as much. This time instead of treating her parents she has just paid for her own family while her sister has treated her parents.

So to say thank you one sister buys mum and dad dinner, the other sister pays for her own family.

whatdotheysay · 19/07/2026 23:05

I can see both sides to this. I think in a way the treat to your parents is gifting them a family meal will all the people they are closest to and love. So it’s not really about who is who, it’s just splitting the cost of such an occasion. Let’s say for example, that your sister could otherwise not afford to bring her husband and son, then that would be a shame for your mum, as she would want them there. I’m not saying that’s necessarily the case, but overall if you view it more as splitting the cost of the event, rather than paying for certain people’s meal, then perhaps you can see your sister’s POV.
Lets saying instead that it was a small party. And you agreed to split the cost. You wouldn’t then sit with the guest list and so ohh wait no I’m going to pay less towards the party because I actually don’t like mum’s friends as much as you do, and I don’t often speak to auntie sue. So you can pay for those guests. Hope you see what I mean.

But then equally I can also entirely see your POV and could argue that point too.
Nobody is necessarily wrong just a different view point and different expectations

ThisTimeWillBeDifferent · 19/07/2026 23:14

Op’s sister is happy for her DF to pay for the three members of her family on a regular basis and therefore thinks she should split equally because she’s so entitled that she doesn’t actually realise that covering her own family’s bill for once isn’t a “treat” for her DF because it isn’t actually his bill. There’s no obligation for him to pay it, he’s just being nice. By TightSis’s accounting, Op is putting her hand in her pocket for her parents, while TSis is effectively saying to DF “because I’m so generous we won’t accept you treating us for once”. The expectation is beyond entitled. It’s bizarre.

Imagine actually saying to your parents that your birthday gift to them is them not having to pay for your family for a change and then being so put out that your sibling doesn’t want to cover the full cost of the gift that you run to your parents to complain and cause drama. Staggering.

Perplexed20 · 19/07/2026 23:15

whatdotheysay · 19/07/2026 23:05

I can see both sides to this. I think in a way the treat to your parents is gifting them a family meal will all the people they are closest to and love. So it’s not really about who is who, it’s just splitting the cost of such an occasion. Let’s say for example, that your sister could otherwise not afford to bring her husband and son, then that would be a shame for your mum, as she would want them there. I’m not saying that’s necessarily the case, but overall if you view it more as splitting the cost of the event, rather than paying for certain people’s meal, then perhaps you can see your sister’s POV.
Lets saying instead that it was a small party. And you agreed to split the cost. You wouldn’t then sit with the guest list and so ohh wait no I’m going to pay less towards the party because I actually don’t like mum’s friends as much as you do, and I don’t often speak to auntie sue. So you can pay for those guests. Hope you see what I mean.

But then equally I can also entirely see your POV and could argue that point too.
Nobody is necessarily wrong just a different view point and different expectations

But you've assumed that the op can afford to pay. They are a single income household.

I honestly dont get this thread.

I'm the person in my family that decided to have children when my sisters didn't. They were all double income families no children. More disposable income. I would have never have expected them to subsidise me.

ForWildCyanTiger · 19/07/2026 23:36

So I guess the way I would think of it is, you’re buying them a £210 birthday gift. In that instance, if it were from both families, I suspect you’d split 50/50 rather than saying your husbands name is on the card so you should pay 2/3 so whilst I see your point and don’t think your way of splitting is wrong, it’s not what I’d have done.

Perplexed20 · 19/07/2026 23:46

As its a birthday, I would have assumed there was a gift plus the meal...

Bellyblueboy · 19/07/2026 23:51

Perplexed20 · 19/07/2026 23:46

As its a birthday, I would have assumed there was a gift plus the meal...

I was just thinking that!

I live how many cheeky fuckers on this thread thinking the sister buying dinner for herself her husband and son is a lovely for her dad😂.

here dad; I am buying my own dinner - sister is buying yours and mum’s. I hope you are proud of how grown up and generous I am
with my sister’s money!

Nesbi · 19/07/2026 23:54

Surprised this is still causing debate. If the OP had paid 50% of the whole bill, her sister’s contribution to the parents meal would have been…nothing. It would literally have been the same as saying - we’ll pay our bill, you can pay for mum and dad and it will be “our” treat.

In what world would that possibly be acceptable? Who in their right might would suggest that? It would just be nonsensical.

wfhwfh · 20/07/2026 00:52

Bigcat25 · 19/07/2026 19:32

Anyone remember a thread a while back where a poster's co-worker tended to order a massive amount of food and drink and his lesser paid coworkers had to contribute towards his share as he always had the bill split evenly. The op was massively supported and cheered on as she stopped letting him get away with it, while he was considered a huge cf. OP's sister is the CF in this scenario.

Yes! That was a great thread. And Mr Greedy nearly soiled his britches when he realised he was going to have to actually stump up for what he’d ordered as opposed to getting subsidised by junior colleagues.

Agree this is analogous here.

Kisskiss · 20/07/2026 01:46

MrsElijahMikaelson1 · 19/07/2026 11:06

That’s exactly what OP did…

No she split it by 6… so she counted the nephew as 1 share..they ordered wine and both the BIL and the nephew didn’t drink

OneSparklyGoat · 20/07/2026 02:19

Kisskiss · 20/07/2026 01:46

No she split it by 6… so she counted the nephew as 1 share..they ordered wine and both the BIL and the nephew didn’t drink

They were charged for 5 meals. Hers was removed from the bill. She still paid for 2 full adult meals, her own and her mother’s. That was more than enough to account for the wine.

Her sister and brother in law paid for their own meals and her father’s meal.

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