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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:
lifeturnsonadime · 18/07/2026 13:43

BringMeHome · 18/07/2026 13:40

If OP pays 50%, her sister isn’t treating her parents at all. Her sister said she wanted to treat her parents so she needs to pay something for them. OP is right.

Different families do things in different ways.

I would assume a 50/50 split. That's what our family do regardless that some end up paying for less than they personally consume.

Both sisters are treating mum and dad by footing the bill for the family meal that the parents normally pay for. Unless otherwise agreed that would be 50/50 split.

MrsElijahMikaelson1 · 18/07/2026 13:43

MissIonX · 18/07/2026 13:33

You're out for a family meal; you say you're treating your parents... I would take that as a 50:50 split (as would 3 other friends sitting here with me).

The idea you only pay for one parent plus your own when your sister now needs to pay for 4 meals when it was you who suggested treating your parents, seems miserly.

Right, so OP and her sister agreed to treat their parents; however, you think OP should pay half the bill, thereby paying for both parents and some of her sister’s bill. OP didn’t agree to treat her sister, why should the sister get a cheaper meal out on OP because they agreed to treat their parents between the 2 of them. 3/5 of the bill was her sisters anyway (as OPs meal was free) but you think OP should still pay half?

MrsElijahMikaelson1 · 18/07/2026 13:44

lifeturnsonadime · 18/07/2026 13:43

Different families do things in different ways.

I would assume a 50/50 split. That's what our family do regardless that some end up paying for less than they personally consume.

Both sisters are treating mum and dad by footing the bill for the family meal that the parents normally pay for. Unless otherwise agreed that would be 50/50 split.

That would be ok if there were equal numbers in both sides of the family. Not 1 person Vs 3, when they had only agreed to treat their parents.

hattie43 · 18/07/2026 13:45

There is so much cheeky fuckery around restaurant bills . If someone says we’ll split the bill it does sound like whatever the bill is we’ll pay half each . However if I knew I had a family of three eating compared to a sole person I would offer to pay more , it’s rude not to . It’s no different to the person quaffing champagne whilst someone else nurses a coke and says oh the bills arrived you ok just to split it 😡

Recklessismymiddlename · 18/07/2026 13:45

KnickerlessFatWoman · 18/07/2026 13:12

Can I ask why you think that would be “quibbling”? I’m not having a go - I’m genuinely interested. To me, it’s just common sense that an adult wouldn’t expect their SIL to partly absorb part of his and his child’s costs.

Maybe quibbling is the wrong word. Dsis has more DCs than me. We always split the bill down the middle, however many we are. Sometimes, all siblings and dcs sometimes no dcs or a few. We never do it per head.

Same for dhs family, we have more than the others, with partners added on, but still all split down the middle. With dh’s family we used to offer to pay extra but rebuffed.

lifeturnsonadime · 18/07/2026 13:45

MrsElijahMikaelson1 · 18/07/2026 13:43

Right, so OP and her sister agreed to treat their parents; however, you think OP should pay half the bill, thereby paying for both parents and some of her sister’s bill. OP didn’t agree to treat her sister, why should the sister get a cheaper meal out on OP because they agreed to treat their parents between the 2 of them. 3/5 of the bill was her sisters anyway (as OPs meal was free) but you think OP should still pay half?

that's what I would do if I'd agreed with my sister that the two of us would treat our parents to a meal for the family.

That's , in fact, precisely what our family do do.

We don't quibble over who gets a fairer deal.

UsherBobble · 18/07/2026 13:46

I think this is so petty, sorry, you should have just paid half.

Ellie1015 · 18/07/2026 13:46

Assuming nephew ate from adult menu I would have counted him and bil as one given they didnt drink wine which can bump the price up. I would have said 2/5ths of cost which is £84. If a lot of wine was included (or nephew had kids menu) then half would be fair.

aVastBehind · 18/07/2026 13:46

I would’ve gone half. The way I see it, dad normally pays £210. You want to treat them so you pay half of what dad normally pays, and your sister pays the other half.

RVectensian · 18/07/2026 13:46

canklesmctacotits · 18/07/2026 13:28

You said your dad always treats people - ie pays 100% - but that your sister and you agreed that this time you would split the bill between you - ie you both pay 100% of the bill.

You didn’t say that you would pay for one parent each in addition to your own meals. That’s a huge gap in misunderstanding and miscommunication.

“Split the bill” means divide the whole thing by the number of people paying. “Treat our parents between us” means each paying for one parent.

And no, you won’t have paid for both parents and she none. You would have paid for yourself, one parent and someone else.

That’s what “splitting the bill” means. If you don’t want to do that, use different (correct!) words.

Edited

Yes, I can see where both interpretations have come from, and both are strictly correct in some ways. So I don't think it is bonkers that the sister thought the OP was splitting it with her.

hattie43 · 18/07/2026 13:47

UsherBobble · 18/07/2026 13:46

I think this is so petty, sorry, you should have just paid half.

I think the trouble is that people who just do this are generally the ones with money . People on a budget can’t always afford to pay over and above what they’ve ordered .

lifeturnsonadime · 18/07/2026 13:49

I mean it's not much different to paying less for nieces and nephews birthday presents because each of our siblings have 3 children and we only have two, in my opinion.

Or do people on mumsnet count every penny this way?

Angelyogini · 18/07/2026 13:50

I come from a mediterranean country and the kind of argument the OP uses seems absurd to me.

You decide to go for a meal to treat your parents, everyone is included, ie I would expect every family member to be counted on the total bill.

You want to pay less, only invite the parents.

arethereanyleftatall · 18/07/2026 13:50

lifeturnsonadime · 18/07/2026 13:23

It's nothing to do with not understanding maths.

The arrangement OP wants is not the 'splitting the bill' arrangement that was made in advance. If 2 people agree to split the bill they pay 50% each.

If OP didn't think that was a fair arrangement she should just have said she'd pay for her and one parent rather than saying she would split the bill .

I think this falls under the umbrella of ‘things that don’t need to be said because they’re blindingly obviously common sense’. So for example, I don’t need to say to my friend ‘don’t eat dog shit’ because it’s common sense. In this situation ‘let’s treat our parents and split the bill’ fairly obviously means ‘let’s treat our parents by splitting their bill’ rather than ‘let’s treat our parents by exactly splitting the bill so that I pay for 100% of their meal and you just pay your own.’

Netcurtainnelly · 18/07/2026 13:51

Good god all this arguing must have spoilt the meal and taken all the fun out of it.

lifeturnsonadime · 18/07/2026 13:53

arethereanyleftatall · 18/07/2026 13:50

I think this falls under the umbrella of ‘things that don’t need to be said because they’re blindingly obviously common sense’. So for example, I don’t need to say to my friend ‘don’t eat dog shit’ because it’s common sense. In this situation ‘let’s treat our parents and split the bill’ fairly obviously means ‘let’s treat our parents by splitting their bill’ rather than ‘let’s treat our parents by exactly splitting the bill so that I pay for 100% of their meal and you just pay your own.’

Ha ha,

You're ignoring all of the posts from people who split bills equally in this scenario regardless of the fact that they personally don't get a good deal from it.

ZenNudist · 18/07/2026 13:53

You're right but it's not a big deal

Awkwardisfunny · 18/07/2026 13:55

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?

Yeah, best thing is for everyone to knock this on the head by always announcing to the waiter that everyone wants a separate bill. Let's normalise this! It takes like 5 mins extra to take a few extra card payments, which every other shop / business manages except restaurants where suddenly, we do a weird group pay thing. It doesn't happen in all countries either, it's just custom / culture.

You definitely don't need to pay for your sister's family's meals: tell her you wouldn't be able to afford to eat out any more if you had to pay for her family, as well as for yourself. She might just have not twigged how unreasonable that would be to expect.

Allseeingallknowing · 18/07/2026 13:55

ZenNudist · 18/07/2026 13:53

You're right but it's not a big deal

It’s lot of money!

Neurodiversitydoctor · 18/07/2026 13:55

Shinyandnew1 · 18/07/2026 13:09

And the nephew

Also drinks, deserts coffees etc.

KnickerlessFatWoman · 18/07/2026 13:56

Jk987 · 18/07/2026 13:32

I know what you mean but I think I would have gone halves. Firstly it’s your own young nephew included so you surely wouldn’t mind treating him?

Think of all the times your parents have treated you and you’ve paid nothing? You should think of it as literally splitting the bill paying for individual meals. I’d always want to treat my family and not quibble over a few pounds.

But my sister has paid nothing on those occasions either! And why would I pay for my nephew instead of his own parents?

Also, while I’m lucky enough that £35 is neither here nor there to me, please remember that not everyone is in such a good position. For some people, a meal out requires careful budgeting, and suddenly finding they’re paying 50% more than planned could be a real issue. Have some consideration.

OP posts:
icouldholditwithacobweb · 18/07/2026 13:57

No way should you have paid 50% of the bill. I am in the same situation, there's one of me and my sister has her partner and their child. If we're splitting the bill, she makes sure I'm not paying for her family too. I have one income, they have multiple - it would in no way be fair for me to foot the bill for her family if the only ones being treated are our parents.

hahabahbag · 18/07/2026 13:57

Sounds like a language / understanding issue. Splitting the bill is 50/50, whereas I’ll pay for one parent you pay for the other is perfectly reasonable as a suggestion but not splitting the bill. You also need to take into account that there’s a child in the mix

bigfacthunter · 18/07/2026 13:58

YANBU although you prob should have discussed it before hand.

For me also couples privilege is a huge bug bear. If you’d brought a date/partner I could see slightly more where your sis would think this split is reasonable.

Trallers · 18/07/2026 13:59

I do agree with you OP 100% but I can see why your sister thought treating the parents meant sharing what dad would have paid between the two of you. It needed a conversation but neither of you realised the other had a different interpretation so that didn't happen!

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