AIBU to stop covering my job-share partner's time off?

Exactly this. You won't be ruining anything. I'd do exactly as others have suggested and say you've just realised you've double booked and can no longer help.

Speak to your line manager about the situation and explain that it’s not working for you. It may be agreed that the other is not needed to cover? Or they might have a word with her.

This! It's quite simple. If it's ok for her to back out last moment, it's ok for you too.
Don't be a doormat. It's great to have a good relationship at work, help each other out but she's not interested in that part. She's a taker only.

What happens if she doesn't cover you? I'm guessing you have your holiday approved and booked officially already. Sounds like a manager issue. Just say you won't be able to cover her and let management deal with cover for both of you.

What happens if she doesn't cover you? I'm guessing you have your holiday approved and booked officially already. Sounds like a manager issue. Just say you won't be able to cover her and let management deal with cover for both of you.

like others am confused by the expectation for one of you to work more days when the other takes leave.

Does your employer agree to & pay you overtime for that?

How many working days extra (overtime) have you worked during her annual leave?

I’d be annoyed by her handling of her requests to you then pulling out of her previous commitment to overtime. Poor of her!

Does your contract not provide for what should happen re cover?

YANBU but it’s your employer’s problem really, you have to be able to take holidays, how work is covered is on them

Is it in your contract to have to find cover for your own annual leave?

Perfect!!

Cancel the dates you have agreed as something has come up and it’s not convenient now.

she can’t have it all

I'm not sure why you're obliged to stand by dates you've agreed to, when she isn't obliged to do so too?
You already don't have a mutually beneficial arrangement, just say that unfortunately on reviewing her dates you are no longer able to provide cover. End of.

I think there’s a lot to be said for just being as barefaced back, you don’t have a working relationship. There’s nothing to work through, and no benefit from trying to explain your feelings. Just go . ‘Hi X, I rechecked my calendar and apologies but I can’t cover any of the days you’ve asked me for. I hope you can work something out.’ Done.

and tell management you booked your holiday, she’s just withdrawn cover but you will still be taking it, they will have to sort something.

I have people who job share on our team and there is no expectation to cover each other as they are employed on a “part time” basis

we ask them if they want overtime to backfill this but generally people work part time because they want to work part time - one lady will do a little bit extra but she’s a single parent so relies on others to then do school runs etc

are you “expected” to do this??? I’m not sure legally they can enforce this

On our team there are job sharers that cover each others leave. So they verbally agree together, then say to manager who sits nearby; X has agreed to cover my leave on these days, I’m submitting the official holiday request now. Then its approved by manager on the leave system, so it’s set in stone.

how’s it work with you op, where’s your manager in this, they need to intervene if things are not being handled in a fair way? Your co-worker is a CF!! So when she said she’d cover, how was this documented? Surely you would tell your manager she’s covering, and then u officially booked your dates with them? So CF letting u down is no longer a you problem as management had already agreed the leave? They need to talk to her

I would actually be quite blunt with this person, but in a polite way so that she knows that I'm not blind to the disparity between us. I would tell her that I'm disappointed that she won't cover for me considering all the times I have covered for her, and this is the very first time I have asked her to cover for me. Then I'd tell her honestly that I'm not prepared for one-way favours and helping those who never want to help me back, so I won't be covering for her any longer - including over the summer.

DONT BE A MUG - withdraw your offer.

Well she can wait to the last minute and withdraw… seems acceptable

You're a mug if you let her get away with this. Just say, I've reviewed the situation and I'm afraid I am no longer able to cover your holiday dates.

You haven't fucked up the working relationship as you haven't got one - she's just taking the piss.

But she agreed to cover her two weeks holiday. What's the difference?

WHAT cordial relationship? She's a CF and its time to call her out.

Why not? The other woman agreed to cover OP's days then went back on her word. This means OP can do exactly the same thing - and, I absolutely would do that, in her shoes.

Agree.

This is the employer's problem

Unless the employer has asked the OP and her colleague to sort this out between themselves.

But if that's the case the OP needs to go back to the employer and ask them to come up with a solution as the OP and colleague can't agree

OP clarity needed - do you get paid for the extra days you do? Does she take it as unpaid leave or is this her annual leave and you are sorting it out amongst yourselves for your boss?

Not a problem really, you push to back to you boss. “Hi boss, just a reminder I have x to y days booked off over the summer. I’ve just checked with job share and she can’t cover those. Thought I better let you know. Also she’s asked me to cover this list of days. I can do all of them, but obviously will be putting in a big overtime bill for the summer and wanted to let you know to budget for it.”

Something like this, I think, but maybe a bit clearer re the “I’m not covering your dates” part.

So after the first bit I’d say “I agree to the dates you’ve requested on the basis you were covering my July x-y holiday. As that’s not the case, I don’t think this mutual cover system is working, so please make alternative arrangements for your periods of leave”