AIBU to refuse to book and pay upfront for MIL?

It sounds as if she allows your DH (and you) to pay for an awful lot, so it would annoy me too.
Your DH needs to wake up a bit.

This.

My mum is similar - it is exhausting. We have many many anecdotes of her causing scenes at restaurants, ‘taking me out’ for my birthday and then making me pay the bill, or confronting my DP while I pop to the loo to make him pay. Yes you can rise above it and pay but it stings when it’s never appreciated or reciprocated.

well it's quite obvious that you hate her . If a grown man can’t sometimes buy his mother dinner or a movie ticket or a ticket into a theme park because his wife doesn’t like it , what a crying shame . Does he monitor every penny you spend ?

And the dinner, and the cinema ticket, and the dinner before that and whatever else she's expected her son to put his hand in his pocket for forever, while she never ever does.

That's the problem, not a theme park ticket and a fan.

At least your dh hasn't inherited the tightness from his Mum. He wants to treat her..let him. His kindness will hopefully break that cycle of meanness and stop it going into the next generation. My dad was a most generous man and l love that so your kids will grow up with that too. Its always better to take the high road.

Your DH wants to pay for her. Do you have to ask him if you can spend money on your parents?

I honestly cannot see a world where this would bother me, except if it was huge sums like buying a house and we had no money for ourselves.

Obviously if there is a drip feed like you are both unemployed and need the money and MIL is a millionaire, then ok. But if you are in stable jobs - and s the cost of a theme park ticket for an OAP (?) worth this anger?

@Shoopshawady just a simple message to her saying ‘looking forward to Friday, theme park tickets booked for everyone and fans bought to keep us cool too. To save transferring any money across it’s probably just easier for you to pay for the lunch. Hope this works for you too. See you soon x’.

If your husband is happy to pay for her (from your join account!) I’d just involve him a little less. For example, just buy your tickets and then tell him you’ve got them for you both and your children. When he mentions his mums ticket, just say you assumed she could sort her own. With the fans, don’t consult your husband first, just buy them for you guys and not his mum, no need to mention buying one for her.

I think you should get the fan, it would be actively cruel not to and it’s not like you can all be holding one and leaving her to sweat. You’re being quite unreasonable there.

And pay for the ticket but when it comes to ice cream, ask her in front of everyone if she wants to pay for them seeing as you bought the tickets.

I get that it is galling but you’ll need to rise above it. Unless it’s damaging your family financially or limiting your options for activities. It will just breed resentment between you and your DH. He might start to fib that she’s paid for things to keep the peace and you’ll be even more annoyed.
Be upfront about what you’re happy for her to join you with and not and try not to get wound up about the costs.

You maybe the mother in law one day! Try to behave as you would wish to be treated yourself…it’s a park ticket and a handheld fan…🙈….not a first class ticket to Australia.

Oh this could be my mum, I booked theme park tickets for us, my parents and aunt and uncle, let them know the cost and aunt and uncle sent the money immediately, mum just didn’t, then half way through the day announced she’d had enough and left. Aunt and uncle also treated my kids to something from the gift shop, the difference between them is embarrassing. Mum also does the ‘I don’t know how to order/pay a bill in a restaurant’ trick and tries to get anyone else to pay for her, now I just say to her why don’t you pay and we’ll all sort it out later and now she doesn’t want to go out to eat anymore 🤣🤷‍♀️

This! Whatever the equation you have with her, and however tight she might have been during his childhood, it seems churlish to resent a few acts of generosity from your husband towards his mother. It isn't as if he's buying her a car. I would actively encourage and support my DP in being generous to his mother, and I wouldn't dream of allowing my mother to pay for such things if she is coming with us.

Keep asking for money up front. What your dh doors is up to him but you can keep asking to make your point.

Thing is - he’s happy to pay for her. He’s invited her along (well gone along with it). Maybe he likes being seen to be generous

really he shouldn’t have let her come - that’s the bigger issue here.

I feel like if he wants to pay for his mum it’s up to him. I don’t run by treating my mum or dad with my partner and he doesn’t with me

I always think it's much harder to accept someone you love being taken for a mug, than it is for you to gloss over it for yourself.
I completely understand how infuriating this must be for you, but I think your only option is to try to see it as your husband being a lovely human being, rather than your MIL being the CF she undoubtedly is. It might be the only way forward for your own peace of mind.

My first thought is that it's a 'theme park' and not one where I'd want to be asking PILs along. My second is that it's a heatwave and that's a fantastic excuse not to waste money on a theme park unless we are talking water based type stuff in air con. The latter may or may not be GP friendly depending on the GP. If you need MILs help and the circs are not too hot, then I'd offer to pay. I'd also address heat and kids.

You always have the choice to not have her come with you. Why spend time with someone you loathe.

It's something so small to get your knickers in a twist about. I mean it's one ticket and a damn £10 fan. Ask for her to reimburse you if you must but blimey take a chill pill.

If your DH wants to sub his mum and it’s not an unreasonable amount of personal spending for him, I think you should suck it up. But if it all adds up to a significant amount and your DH is still spending as much on himself as you do on you, then I would start putting my foot down a bit. Either explicitly, or just by taking control and asking her for it myself. E. g. as PP suggested, text her saying something like “I’m ordering ticket tomorrow at 4, if you’d still like to come, please transfer £x into my account before then, otherwise I’ll assume you’ve changed your mind. DH also mentioned you might want one of these fans I’m getting for the rest of us [link], if you’d like me to order it, add another £y. Hope you can come, DC is really looking forward to it. “

Do not talk to your DH about asking her for money when you do things he wants to include her in, just do it yourself and require the money up front. If she says she’ll give it to DH when she sees him tell her that’s inconvenient as you need the money in your account to order but if she wants to order stuff herself, obviously that’s fine and would probably be easier on you.

My mother is like this. It’s infuriating.

Can you just rectify the accounts and ignore it?

So he takes £10 joint for her ticket (£5yours, £5his), so you take £10 too