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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:
Trainup · 19/07/2026 10:04

clearly there has been a misunderstanding. I can see both sides and hopefully you’ll discuss it with your sister and come to an agreement .. but why on earth have you both discussed it with your parents? Surely that has taken away from the ‘treat’ completely and your dad probably wishes he’d just paid the damn bill. Your sister didn’t need to tell your mum about the money issue and when your mum mentioned it why not just say ‘oh I hadn’t realised, I’ll reach out to sister’

mn5962 · 19/07/2026 10:04

@KnickerlessFatWoman I can see how this ‘split’ issue has happened but I am with you OP. That said it obviously wasn’t clearly understood at the time. Nobody’s fault just a misunderstanding.

you and your DS agreed to treat your folks….in hindsight’s maybe spelling out what that meant would have avoided this but it is what it is.

how have things been left? It’s not worth falling out over £35…..believe me I’ve seen it in my own family.

Rainbows246 · 19/07/2026 10:04

Shinyandnew1 · 18/07/2026 13:12

OP should pay
35 for her (and that’s being kind as her mains was taken off)
35 for her mum.

sister/BIL should pay
35 for sister
35 for brother in law
35 for nephew
35 for dad

yes, they are paying more and that’s because there are more of them eating. You shouldn’t be out of pocket because there are three of them and only one of you!

i agree with this. Why should Op pay more to cover her sisters family.

She isn’t splitting the bill she is paying for a parents share… it’s different. Also if her main was taken off she is still paying more regardless.

BunnyLake · 19/07/2026 10:04

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.

I think your ‘mind’ needs a reboot.

If the parents normally pay for a family holiday and sisters wanted to treat them instead would you expect OP to contribute to sister’s family’s holiday expenses too?

Hammite · 19/07/2026 10:05

I'm with you OP on the principle. If it were just you, sister and parents then 50:50 makes sense. Anyone else on sisters side should be covered by sister. She only has 2 extra people, but what if they had 4 extra or more - is splitting the whole bill fair then?

Wadsworthy · 19/07/2026 10:05

Anyone with any self respect would not be demanding the single person pays the same as the couple with a twelve year old.

Well, quite.

Woodfiresareamazing2 · 19/07/2026 10:07

Monty36 · 19/07/2026 10:01

If someone said to me shall we go halves on the bill as a treat to mum and dad I would assume half of the total cost.
Otherwise a person would ask if you would pay for mum and I pay for dad and we pay for ourselves.

Edited

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.

Oneofthworher · 19/07/2026 10:07

I really don’t know why people keep banging on about you agreeing to split the bill, when nowhere in your post does it indicate that you agreed to split the bill. You agreed to treat your parents.

If I turned up with my husband and child and my sister alone there is absolutely no way I would expect my sister to pay 50% of the bill and I think it’s CF behaviour to expect so. I would expect her to pay for her own food plus half of parents.

coachinghelp · 19/07/2026 10:08

There are two of them and one of her! If a conversation goes like:

Sister: Let's treat mum and dad
Other sister: Yes let's
BIL: Ok great let's us all treat them, shall we split it
Both sisters: sounds good

That means three people have agreed to split and that does not mean 50/25/25 on any planet

Notmycircusnotmyotter · 19/07/2026 10:09

I can see both sides but I'm quite shocked the OP is being so aggressive, so I'm inclined to side with the sister.

BunnyLake · 19/07/2026 10:09

Candy24 · 19/07/2026 10:01

You sound simply awful OP and I would have paid half as agreed. I think your rather off putting with your demeaner. I would pay the extra and say sorry I misunderstood as your at this point not worthy of any form of sympathy for your crap behaviour

The only thing awful is your comprehension skills. But at least you’re not alone, there’s an abundance of it on this thread.

XelaM · 19/07/2026 10:09

OP I don't know why you're getting such a hard time on here. I completely see your point.

Did you explain it to your sister? What did she say?

BunnyLake · 19/07/2026 10:12

Notmycircusnotmyotter · 19/07/2026 10:09

I can see both sides but I'm quite shocked the OP is being so aggressive, so I'm inclined to side with the sister.

I normally disapprove of that kind of attitude but honestly I can understand why OP is getting so irate and frustrated. Some of the density on here has been really frustrating and I’m not even the OP 😁

TitsAndAssChangedMyLife · 19/07/2026 10:13

Notmycircusnotmyotter · 19/07/2026 10:09

I can see both sides but I'm quite shocked the OP is being so aggressive, so I'm inclined to side with the sister.

Keep clutching those pearls 🙄

BlueMum16 · 19/07/2026 10:13

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.

She's a CF. Usually gets a free meal and now complaining because she not only has to pay for her own family but a share towards her parents.

She knows she's in the wrong otherwise she'd have messaged the OP about the bill and not her mum.

Wowwhataworld · 19/07/2026 10:14

A simple misunderstanding on your sisters part which you should speak to her about. Tbh I agree with you but last night your responses became more and more rude, angry and nasty and it honestly made me change my opinion. If it’s as simple as this you phone your sister and explain and it should all be sorted - the end.
To argue back and forward with people giving their opinions (which is what you asked for) you just came across as very awkward and rude. You have pointed out that for some people £35 is a lot but insinuated it isn’t for you therefore I’m wondering if you are just being awkward with your sister on some sort of competitive sibling level.

OneFineDay22 · 19/07/2026 10:14

IffWhite · 19/07/2026 09:37

I think the point is that you dad normally past for the whole bill, yes?

So by relieving him of thet duty, it sounded like you were going to pay the whole bill between you and your sister.

I can see how that translated at 50/50.

I can understand how the sister got the idea they were going to pay 50/50. But at the point that she (or her DH) then received £70 she had an opportunity to realise what OP had meant by “treating their parents”. If she wanted to make a thing about OP not having contributed to her DH’s or DC’s meal, why ever she would have thought that reasonable, she should have taken it up with the OP.

Morepositivemum · 19/07/2026 10:15

Woodfiresareamazing2

technically two of them talking they would mean two of them though? I don’t know- I don’t even agree with myself I just see how it can happen and without even thinking either her sister or op is a cf!!!

YourWildAmberSloth · 19/07/2026 10:15

KnickerlessFatWoman · 18/07/2026 13:03

Where do you get that I thought my parents were paying for themselves? I said, the plan was to treat our parents.

The bill was £35pp. I paid £70 - my share and one parent’s. The rest of the bill was my sister’s share and one parent’s (another £70) and then my BIL and nephew’s shares (the final £70).

What about drinks, dessert etc? Was the actual bill £210 like you've said or was it less? If the meal was £35 per head, I'm assuming that was for more than a main, so if only your main was deducted, you would still be charged something. 'Treating your parents' and 'splitting bill' are actually 2 different things.

Duckswaddle · 19/07/2026 10:16

Bloody hell….

TitsAndAssChangedMyLife · 19/07/2026 10:16

Wowwhataworld · 19/07/2026 10:14

A simple misunderstanding on your sisters part which you should speak to her about. Tbh I agree with you but last night your responses became more and more rude, angry and nasty and it honestly made me change my opinion. If it’s as simple as this you phone your sister and explain and it should all be sorted - the end.
To argue back and forward with people giving their opinions (which is what you asked for) you just came across as very awkward and rude. You have pointed out that for some people £35 is a lot but insinuated it isn’t for you therefore I’m wondering if you are just being awkward with your sister on some sort of competitive sibling level.

Yes @KnickerlessFatWoman, you’ve been tewibly tewibly wude. Why can’t you be nice and quiet, like a good little girl?

TitsAndAssChangedMyLife · 19/07/2026 10:17

YourWildAmberSloth · 19/07/2026 10:15

What about drinks, dessert etc? Was the actual bill £210 like you've said or was it less? If the meal was £35 per head, I'm assuming that was for more than a main, so if only your main was deducted, you would still be charged something. 'Treating your parents' and 'splitting bill' are actually 2 different things.

And the OP only said she was doing one of those things…

Heathertrott2 · 19/07/2026 10:18

Hi @KnickerlessFatWoman I'm interested to know this. If you had paid for the full bill on YOUR card rather than your Bil's, and they transferred you £105 instead of £140, would you have said something to your sister?

EvieBB · 19/07/2026 10:18

Notmycircusnotmyotter · 19/07/2026 10:09

I can see both sides but I'm quite shocked the OP is being so aggressive, so I'm inclined to side with the sister.

I'm shocked you expect op to remain calm when she's being unfairly criticised!

Shinyandnew1 · 19/07/2026 10:19

OneFineDay22 · 19/07/2026 10:14

I can understand how the sister got the idea they were going to pay 50/50. But at the point that she (or her DH) then received £70 she had an opportunity to realise what OP had meant by “treating their parents”. If she wanted to make a thing about OP not having contributed to her DH’s or DC’s meal, why ever she would have thought that reasonable, she should have taken it up with the OP.

This-your sister has assumed something you didn’t mean.

Have you talked to him about it now?

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