AIBU to think a junior probationer’s month abroad request is unreasonable?

You need to speak to HR. My company would be a no, because of security, tax, insurance, loads of reasons. There are pribably things in the work contract too.
It isnt a simplr practicality of working and service levels issue.
Take it to HR as this is out of your scope.
Explain to the junior that you can not approve it but you will pass this to HR to review. It maybe that they can take unpaid leave or some other option.

Sly and definitely premeditated. They know what they’re planning to do.

I think if you wanted to be very, very kind you could sit them down and explain how totally off the mark they are. Tell them calmly and in a mentoring capacity that this is completely unacceptable and not how work works. Say you are giving them the benefit of the doubt that somehow they hadn’t understood this. Explain that you are not approving the leave or remote working. Then give them the option to either cancel the trip at their own cost, or resign.

jt is cheeky but as said above your options are suck it up or say no, not granted and be prepared for him to either leave or sack him

If hiring / training costs to replace them aren’t too high would probably say a flat no to any leave other than the annual leave they’re due, and hope they resign, or fire them if they go anyway. since someone who behaves like this so soon is likely to continue to do problematic things later when it’s harder and costlier to fire them.

Not sure this person sounds like a good fit in the long term. It’s unlikely to be the only time once they get away with it.
also I don’t know on Aus rules but there can be tax implication of working abroad especially in jurisdictions like India and China so often they are refused. At our place for some time you couldn’t even have access to work email when you go to India.

I would refuse.
This is the real world.
In my business we are not allowed to work remotely in EU countries due to tax rules and can't work outside EU due to data protection rules.
If they had explicitly said at recruitment "I'm going abroad for 4 weeks a month in" would you have offered them the job, or picked someone else.
Sounds like a cheeky fucker to me.

It doesn't bode well for the future. To be so brazen and cheeky when you have barely started the job demonstrates an attitude that puts the job at the very bottom of their priorities.
Have they never worked before?
I can't imagine a workplace where staff routinely book holidays without prior approval.
If it's her very, very first job it might be worth explaining that leave can only be taken with prior approval in future. On this occasion she can take the whole period as unpaid leave but it will never happen again.
I would definitely not bend over backwards to allow her to "work" during the holiday.
If she's only just in the job she can't be irreplaceable.

I'd just show them the door. Many employers don't allow more than 2 weeks without extenuating circumstances let alone booking without checking at all. A special blend of stupidity and entitlement.

Do you think they had already booked the month away before the job offer?
When they 'briefly mentioned in passing' did you pick up on this and clarify what they meant, or make it clear that was not an option so early in their job? They might have thought 'briefly mentioning' without any pushback from you meant 'OK'.

That said, I have a 25 year old who is currently in probation in a new job. Before she started she clearly (not briefly!) mentioned some prior booked summer commitments and these were approved as a/l at the discretion of the hiring manager. Much as she would LOVE to go travelling for a month, there is no way she would book this after the event and there is no way she would be dictating terms. Not all 25 year olds are piss-takers. It does sound like this one is though.

With the extra info, no, fuck that shit

Refuse permission for any leave at that time. They can either cancel the holiday or resign. And if they cancel, put in one day a week work from office/in person meetings so they can't attempt to sneak off and do it anyway.

They won't lose thousands. They will go.

You need to look for a replacement.

YABU to even consider agreeing to them working abroad. Cheeky fuckery. If your employer has a woolly policy on that, they’re silly.

Where I work a request for unpaid leave so soon into employment would be swiftly declined and they’d need to shorten the trip, cancel it, resign, or go on leave unauthorised and risk being disciplined - though probably not fired.

Unpaid leave and extend probation.

Ive had a similar situation, didnt approve it, they left rather than lose the money on the holiday, oh well. Not to worry. Very easily replaced with someone who didnt take the piss

A lot of companies would just quietly fail their probation just for asking. It is so witless its breathtaking. It raises questions about their judgment.

It would be generous of you to say no, allow them to remain employed and learn a valuable lesson.

If you relent, this would (IMO) be the first of many special requests, better desk, ergonomic chair, WFH, compressed hours, leave of absence, you name it.

Nope. I would let them go - from the job, and sayonara.

For me: Cancel trip or resign.

Even unpaid leave is a massive favour I’d only consider IF it had been discussed well in advance. I wouldn’t be offering any solutions to this, and the “do first, ask later” attitude to force the issue is not one I’d welcome.

Quite possibly one of the most entitled posts I've read.
You don't book a month off in the adult world without permission.
Not a chance would i be agreeing to this.

“They are 25 and would lose thousands” Ain’t life a bitch?

Neither of which is anything you can control. At 25 I would expect someone to have some understanding of how working practices pan out. Presumably they have either been in work before or have been studying , either way they will have met up with situations when they need to concede that the needs of the work or studying environment take precedence over personal wishes whether this be working hours, attendance, deadlines etc.

The money situation is also not your concern, they have presumably booked travel arrangements and sorted out accomodation, if they have been stupid enough to do this before checking that the leave and salary arrangements were ok with the employer then that is down to them.

In that case definitely just let them go. There must be plenty of other junior staff who’d want this opportunity?

From bitter experience..,.

I approved extended leave for one employee, three weeks at a time of year only two were allowed so he could go to South Africa. He then decided he wouldn't be back for another week as he wanted to tag on a week visiting his girlfriend's parents in Scotland. He didn't actually apply for this, he just let slip that he wouldn't need to worry about jet lag as he would have that week to recover!

When told no, he had a massive screaming tantrum and said that the company should not have its long established Christmas shutdown that year and we could all take that week off.

Err no.

Nip it in the bud, cheeky fuckers are as cheeky fuckers do and it will only get worse.

Rereading this, I would say this is leave/wfh abroad request has not been granted, please cancel the holiday or take what’s been accrued so far as holiday.

Also imagine the outcry in your company with colleagues if they find this has been approved. A whole can of worms could be opened with others wanting similar treatment.