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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:
nomas · 19/07/2026 20:17

Cynicalist · 19/07/2026 20:06

Sorry, how old is your nephew?! If he’s a child and not drinking and not eating much , I wouldn’t even be counting him in the numbers… so then it becomes £210 over 5, so £42 each making yours £84 and there’s £126 which probably seems more reasonable…. Unless nephew is a fully grown adult I wouldn’t be counting him in, or would you expect him to use his Henry card and pay the £35 if everyone were saying there own share?

The restaurant still expects the £35 for the meal that the 12 year old child ate, so why is it up to OP to cover this instead of his actual tight arse parents?

RabbitlessMagician · 19/07/2026 20:22

If you had held a party for him surely you and your sister would pay half of the cost? Not quibbled over which side of the family got more value ie ate more , danced more etc

This is a false equivalency. Unless you’re ordering individual meals for guests, a party will cost a certain price for the venue hire, food for however many etc.. Plus if they’d been hosting a party, wouldn’t all the guests be people their mother wanted there? Therefore there’s no “Which side of the family got more value” question here.

OP isn’t saying she wants to pay less based on her enjoyment or otherwise of the meal 🙄 The cost was directly influenced by the fact that she is one person while her sister is part of a family unit of three.

RabbitlessMagician · 19/07/2026 20:24

Cynicalist · 19/07/2026 20:06

Sorry, how old is your nephew?! If he’s a child and not drinking and not eating much , I wouldn’t even be counting him in the numbers… so then it becomes £210 over 5, so £42 each making yours £84 and there’s £126 which probably seems more reasonable…. Unless nephew is a fully grown adult I wouldn’t be counting him in, or would you expect him to use his Henry card and pay the £35 if everyone were saying there own share?

That’s by the by really. OP’s sister hasn’t said “You should pay more for than £70 because son’s meal was cheaper”. She’s said she wants a straight split.

forgivingfiggy · 19/07/2026 20:25

You offered to split the bill. That’s half. 50/50 regardless of who is there or who ate.

EvieBB · 19/07/2026 20:29

forgivingfiggy · 19/07/2026 20:25

You offered to split the bill. That’s half. 50/50 regardless of who is there or who ate.

Jesus H. How many times does OP need to explain? She offered the go halves with treating their parents ....nowhere does it say she was happy to split the whole bill 50/50

RabbitlessMagician · 19/07/2026 20:30

”Split the bill” is fast becoming the new “Cancel the cheque”!

Meeesh · 19/07/2026 20:34

Why did you wait until now to argue about the bill. You and your sibling agreed to split the bill. That means you pay half! Next time, if there should ever be one... get organised in advance and make sure you are who is paying for what!

croydon15 · 19/07/2026 20:37

I think that your Dsis is bu to go to your DM about the bill, it was your DM' birthday treat so she should have spoken to you directly if she had a problem with your portion of the bill. You said that you will treat one of your parents and that's what you have done.

Zaza2020 · 19/07/2026 20:39

Does no one ever communicate anymore. A quick text to your sister and you are done. Gosh!!

Perplexed20 · 19/07/2026 20:40

This thread is so weird or people are bad at maths. OP, YANBU.

Birthday meal treat for mum & dad.Their bill would be £70
Sister + bil+ child = £105
Op = £35.
Total bill = £210

If divided in half

Op= £105
Sister =£105.

Therefore op has paid for both parents and self. Sister has paid for her family and no contribution to 'treat' - therfore can't claim generosity.

Op pays £35 +£35 = £70 - which is self plus half of 'treat'
Sister pays £105 +£35 = £140 - which is family plus half of 'treat'.

I don't get why Op shoukd pay for nephew. And say this as only parent amongst my siblings.

I would be fascinated to see others reasoning other that 'because'.

EastGrinstead · 19/07/2026 20:46

Zaza2020 · 19/07/2026 20:39

Does no one ever communicate anymore. A quick text to your sister and you are done. Gosh!!

Where OP is concerned?

I very much doubt it. You only need to read her obnoxious replies to any poster who had a different opinion to her.

Normal discussion is not within the OP's repertoire.

Perplexed20 · 19/07/2026 20:49

EastGrinstead · 19/07/2026 20:46

Where OP is concerned?

I very much doubt it. You only need to read her obnoxious replies to any poster who had a different opinion to her.

Normal discussion is not within the OP's repertoire.

What is the opinion though?

It's maths.

RabbitlessMagician · 19/07/2026 20:50

The irony being that you’re being really quite vicious about the OP, @EastGrinstead.

RabbitlessMagician · 19/07/2026 20:52

Meeesh · 19/07/2026 20:34

Why did you wait until now to argue about the bill. You and your sibling agreed to split the bill. That means you pay half! Next time, if there should ever be one... get organised in advance and make sure you are who is paying for what!

I honestly despair.

Perplexed20 · 19/07/2026 20:54

@EastGrinstead so according to you sister gets to take kudos for treating parents whilst actually putting no money towards it . Why?

EstoyRobandoSuCasa · 19/07/2026 20:55

Clavinova · 19/07/2026 14:28

He should feel guilty about expecting his single sister in law to cover part of his meal.

His single sister-in-law deprived him of a free meal in the first place. It was her idea.

I assume he drove his own family. Did you think OP should have also chauffeured them?

Do you think the brother-in-law should have chauffeured anyone? The other adults were all drinking alcohol. Do the sister/brother-in-law live nearby or did they travel some distance?

What is it with this BIL and people thinking he always deserves a free meal? Someone else must always pay for him, whether it's his PILs, wife or SIL. Baffling.

Whothought · 19/07/2026 21:02

I can’t read anymore of this without commenting. I have read all of OP’s posts but not quite all of the responses so forgive me if I’ve missed something.
OP is right. My sister and I usually fight to pay the bill. No way would either of us expect the other to pay more than is their true share. This just wouldn’t happen. Your Dsis is being wholly unreasonable for both expecting you to pay more and maybe even more so for involving your Dmum. It is shocking behaviour and she is guilty of possibly causing a family rift. I just don’t get why people are piling up on OP, she is blameless in this, her sister is not.

MyEasterBonnet · 19/07/2026 21:09

i think OP split the bill the correct way; I don’t know why anyone thinks any differently.

Perplexed20 · 19/07/2026 21:09

@Cloudtime why is the op tight but the sister isnt?

Clavinova · 19/07/2026 21:10

Perplexed20 · 19/07/2026 20:40

This thread is so weird or people are bad at maths. OP, YANBU.

Birthday meal treat for mum & dad.Their bill would be £70
Sister + bil+ child = £105
Op = £35.
Total bill = £210

If divided in half

Op= £105
Sister =£105.

Therefore op has paid for both parents and self. Sister has paid for her family and no contribution to 'treat' - therfore can't claim generosity.

Op pays £35 +£35 = £70 - which is self plus half of 'treat'
Sister pays £105 +£35 = £140 - which is family plus half of 'treat'.

I don't get why Op shoukd pay for nephew. And say this as only parent amongst my siblings.

I would be fascinated to see others reasoning other that 'because'.

Sister has paid for her family

The brother-in-law got lumbered with the bill. Not his mother, the food was poor, he didn't have any of the wine, and his wife and sister-in-law misunderstood who was paying what. I feel sorry for him.

eminthebigsmoke · 19/07/2026 21:11

I agree with you OP and I think it was crap
form of your sister to bring it up with your mum instead of you.

ThisJollyLemonMoose · 19/07/2026 21:15

Clavinova · 19/07/2026 21:10

Sister has paid for her family

The brother-in-law got lumbered with the bill. Not his mother, the food was poor, he didn't have any of the wine, and his wife and sister-in-law misunderstood who was paying what. I feel sorry for him.

Oh poor BIL, having to pay for his own meal after freeloading from daddy in law all this time 🙄

Clavinova · 19/07/2026 21:16

EstoyRobandoSuCasa · 19/07/2026 20:55

What is it with this BIL and people thinking he always deserves a free meal? Someone else must always pay for him, whether it's his PILs, wife or SIL. Baffling.

The BIL paid the restaurant bill last weekend - he was willing at least to contribute £105.

Perplexed20 · 19/07/2026 21:17

@clavinova did the sister divorce her parents when she got married? Are they no longer family? So therfore she doesn't have to contribute to their treat?

But this thread has explained something bigger for me. For you, clavinova, feelings trump logic.

EstoyRobandoSuCasa · 19/07/2026 21:18

EastGrinstead · 19/07/2026 20:46

Where OP is concerned?

I very much doubt it. You only need to read her obnoxious replies to any poster who had a different opinion to her.

Normal discussion is not within the OP's repertoire.

I thought OP's response to the poster who accused her of having an alcohol problem was funny.

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