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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:
EvieBB · 19/07/2026 10:20

So, has anything been resolved op? Did you manage to speak with your sister yet?

Newyearawaits · 19/07/2026 10:20

TitsAndAssChangedMyLife · 19/07/2026 09:56

What don’t you understand about it? More people eating means they pay more. Seems pretty simple to me.

Because it's not how my mind works when it comes to family.
I would feel very uncomfortable with splitting bills.
Everyone is different

CinderellaGotOld · 19/07/2026 10:24

KnickerlessFatWoman · 19/07/2026 09:21

But if I pay half, she hasn’t spent anything on my parents’ meals. With a 50/50 split, she and her family just happen to have been there while I treated my parents.

I don’t know how I can make this any simpler.

You still seem to struggle with the concept that the whole meal was the gift (not just covering your parents costs). And whilst you have said it’s different to a painting for example as it depends on the number of attendees, presumably your parents also wanted your BIL and nephew there so it’s not as thought they were tagging along for a freebie - they were part of the gift.

I understand your point of view but can also equally see your sister’s expectation. I am not saying there is one of you over the other that should just accept the £35 difference but you seem completely unable to understand why your sister may have thought what she did

Khanga27 · 19/07/2026 10:26

My logic is the same as yours op - if I split with a sibling, because of my partner and child I pay more. But initially my sibling did suggest 50/50 which I refused as not at all fair on them.. I therefore think it’s just a miscommunication/misunderstanding that can be resolved with a conversation with your sister rather than a thread that is way more dramatic and combative than the situation itself.

edited for typo

Marieb19 · 19/07/2026 10:27

OMG hiw had this stream has descended into such hate. There was obviously a misunderstanding as to how the bill would be split and uf I were the sister I would expect to pay more because there were 3x the number in my family. Rather than descend further into abusive interactions on line, I would pick up the phone to your sister to discuss why you paid what you did. If she is upset or skint I would offer to pay the difference for the sake of family harmony.

Wadsworthy · 19/07/2026 10:28

Birdsongsinging · 19/07/2026 08:23

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

Yes, @Birdsongsinging

OP pays £70 = £35 for one parent's meal & £35 for her meal.

OP's sister pays £140 = £35 for one parent's meal & 3 x £35 for herself, her DH, & her son.

So each of them has spent the same amount on their parents' treat meal.

But OP's sister thinks OP should have paid £105 = £70 for 2 parents' meals & £35 for her meal

OP's sister thinks she [the sister] should have paid £105 = 3 x £35 for herself, her DH, & her son. No payment for a parent's meal there, is there?

Do you get the problem @KnickerlessFatWoman has with her sister's logic now?

And that's before we consider the sister whingeing to their mother.

cubistqueen · 19/07/2026 10:29

@KnickerlessFatWomanive only read your responses but omg I can’t believe the absolute denseness of some of the people on this thread. Of course it meant you and your sister were going to share your parents costs. No way would I allow my childfree, single sister to pay towards my childrens’ meals. They are my responsibility (don’t have a partner but same applies) and conversely no way would I pay extra because my brother ans his 5 kids joined us - they are his responsibility.

hopefully by now your sister will have realised her mistake and the drama will only exist on here.

My childfree sister does tell me that this happens to her frequently - the expectation that she pays for other people’s children. Sometimes without our own family. It sucks.

powersthatbe · 19/07/2026 10:30

OP, your sister is a massive tit for mentioning this to your Mum. Totally unnecessay and unreasonable. Does she have form for snitching to your parents on you?

My Dsis and I often treat my DM and its a case of ‘I’ll pick up mums tab’, never equal split as I have 2DC and she has none. I would never treat my mum and then discuss a quibble with her after….completely ruins any apparent treat.

researchers3 · 19/07/2026 10:36

BlackCat14 · 18/07/2026 13:05

I think you’re right, but it should have been discussed at the time. To say “split the bill” does suggest an equal split so I can see why they thought you’d pay starlight up half the bill. But you shouldnt be subsidising the three of them, I agree you should just pay for one parent each. But I definitely would’ve made that clear at the time.

This, although it is very obvious to me that it would be hugely unfair to have split the bill in half!

I can't believe your sister has involved your mum in this when it was her birthday.

I wouldn't bother discussing it tbh, she is so obviously in the wrong and will probably run off to y9ur mum again if you do.

elessar · 19/07/2026 10:38

So @KnickerlessFatWomanhave you raised it with your sister since your mum told you what she said?

Tauranga · 19/07/2026 10:43

lifeturnsonadime · 18/07/2026 13:06

Sorry I misunderstood.

However in my mind if both siblings have agreed to treat parents by splitting the bill then, unless otherwise agreed, then I would think 50% of bill each regardless of the fact that there are are more on their side of the family.

This happens frequently for me / dh as we have less kids than our siblings on both sides. We don't ask the other families to pay more we just split equally.

This is not really fair of others to take advantage of you.

Monty36 · 19/07/2026 10:44

Woodfiresareamazing2 · 19/07/2026 10:07

That's completely reasonable.

However, in this case no-one said that.

What was agreed in advance by the sisters was that they would treat their parents.

Which is what OP has done - paid for one parent (plus herself).
Sister pays for one parent plus herself (her, her DH and DC).

Perfectly fair and completely reasonable.

Indeed. The OP agreed to treat mum and dad. Because mum and dad always pay for everyone else when they go out. I doubt mum paid for one child and the other paid for the other. They just paid for the lot.
She and her sister agreed they would pick up the tab this time.
I would have taken that to mean split the bill. And not that one sister pays for one parent and the other pay for the other parent. And the rest is all separate.
But that they would pick up the total restaurant bill together.

bigboykitty · 19/07/2026 10:46

I completely agree with your thinking, OP. Your assumption that between you, you would cover the costs of your parents' meals between you was fair. I'm not sure why you started an AIBU thread because you seem certain anyway and you seem to be coping quite badly with anyone who disagrees with you. AIBU is always full of contrary and obnoxious opinions. What were you hoping would happen?

FashionVixen · 19/07/2026 10:48

OP, kindly, are you ok? I’ve just read through all your posts and you seem extraordinarily angry with folks who are just answering your (imo) not unreasonable question - I’d have had the same thoughts but we use Splitwise app so less likely to come up. I hope that the sun is shining where you are and you can take yourself off for a nice stroll and a fancy coffee.

2026letsgo · 19/07/2026 10:50

TitsAndAssChangedMyLife · 19/07/2026 09:51

Except it isn’t, because a cake costs what it costs. If you’re going halves on a cake, the cost isn’t going to change if someone only has one slice and someone else has two. Okay, maybe you need a bigger cake for a bigger party, but that’s going to be a difference of what, a couple of quid? Two extra meals is a very different thing.

If we’re going to go with a cake analogy, this scenario would translate into OP’s sister saying “We bought you a cake, Mum!” when actually OP had paid for it.

You have misconstrued the analogy by leaving out the Ops dad though.

Say the dad normally buys a beautiful cake for his wife’s birthday but the sisters decide they will pay for it instead, I think most people would agree paying half each was fair.

There’s nothing fair about their dad paying for everyone if you are just doing a meal per individual cost

Databreach · 19/07/2026 10:50

Really really weird responses from some people here. Usually on mumsnet posters are absolutely for paying for their fair share, and not having others cover for their portion etc. mind blowing double standards

Indaloo · 19/07/2026 10:51

Your wrong.

Not because your not paying for their meals.

But because you have divided the head amount by 6 which is unreasonable because you have a child there.

So 210 divided by 5 = 42.50 a head. Times that by 2.5 as a fair split and you get 105 so you just should have paid that imo. If you’re going to be stingy then take the 20 quid off. But you still shortchanged them.

Clavinova · 19/07/2026 11:00

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EstoyRobandoSuCasa · 19/07/2026 11:03

YANBU OP. You and your DSis were treating your parents. Goodness knows why anyone expects you to subsidise BIL (or their son, given that he has both parents to pay for him and you’re on your own).

As is so often the case on AIBU, I think many of the responses are bonkers.

Ocelotfeet27 · 19/07/2026 11:04

Just speak to your sister about it and explain your reasoning. Hopefully she will understand and say ah ok fine and all will be well. Much better than arguing with everyone ob here.

MyOtherProfile · 19/07/2026 11:06

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Rude. Not surprising though.

I guess you missed that OPs meal came free because there was an issue. So that evens out the alcohol.

ScribblingPixie · 19/07/2026 11:06

It's just a difference of opinion on whether the family meal was the gift or the two parents' meals was the gift. Given that the dad usually pays for everyone, it's easy to see why the sister thought they were splitting the meal, but I'd have thought once the OP explained why it wasn't fair she'd have understood. Bit of a storm in a teacup.

MrsElijahMikaelson1 · 19/07/2026 11:06

Kisskiss · 19/07/2026 01:50

Agree you shouldn’t pay half , but maybe it should have been split by number of adults ( 210/5) , how much did your nephew eat anyway

That’s exactly what OP did…

EstoyRobandoSuCasa · 19/07/2026 11:07

Databreach · 19/07/2026 10:50

Really really weird responses from some people here. Usually on mumsnet posters are absolutely for paying for their fair share, and not having others cover for their portion etc. mind blowing double standards

People are so obtuse on AIBU that I can understand why people are tempted to post reverses. I bet if the sister had posted from her point of view, she would have been torn to shreds!

PrettyPickle · 19/07/2026 11:09

@KnickerlessFatWoman (love the name bytheway!) I think this is getting out of proportion to the issue at hand. I do get that you shouldn't have to pay for both parents, I fully support you on that. But I just need a bit more info please.

Forgive me but this seems to be down to a misunderstanding about the interpretation of splitting the bill, which can be taken in many ways. Your nephew is 12 so that's adult portions. Six people present so divide total bill by 6 or each of the daughters families pay their own way plus a parent each, that is a different matter, that's not splitting the bill and from what you have explained this is the scenario in this case, you did not agree to split the bill but for each sister to pay for one parent.

So the question of the final balance was complicated by the fact they would only take one card, or this would have been resolved at the table as the discussion would have been had at that time. Embarrassing but there we are.

So if the bill came to £210 was that after they deducted your main or before? Either way if you still paid £70 which includes full £35 for your meal (the mains of which you did not get, that is more than fair.

I would send your sister, a quick friendly text saying you hope she has the money. As promised you have split the cost of your parents and you have paid for one and them the other. I wouldn't bring up anything your parents have told you. Just let it drop.

And this is the thing, all this could be avoided by a simple conversation and you will know better for next time, and there needs to be a next time or you will all spoil it for your parents. Next time, and forgive me if this is what you thought you had already done, because your family don't seem to get this, tell her by text you are all paying for yourselves except you will go halves on the parents meal so they do not have to pay.

Families eh!

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