My Employer has not passed on my PAYE to HMRC (nor my student loan repayments to Loan peopl).

Zombat5

Ok, here is what I know (it's not straightforward and makes little sense but that's really due to the shenanigans of daughter's previous boss plus HMRC being understaffed and in a muddle)...

Shortly after daughter moved to her new firm two things happened at almost the same time. Firstly she received a tip off from a previous employee of the old firm saying she should check with HMRC about whether her deductions for tax and NI had been passed on. Secondly she received a letter from HMRC saying she was due a tax rebate and she should phone them about it so she did. HMRC informed her that the rebate was due to her not working for 2022/23. She said she had worked for that year. HMRC said they'd received a letter from the old firm in April 2023 saying that she had not received a salary in 2022/23. They then received another letter from ex-boss in May 2023 saying that she had received a salary but no deductions had been made by his firm (at which point I assume HMRC thought she was
self-employed).
She then sent letters to NI and HMRC with copies of all her payslips which showed all the deductions. NI wrote back saying ok that's fine we accept your evidence and we'll update your record.
She heard nothing from HMRC so checked on the HMRC app which said she owed them £5k.
She phone HMRC again and unfortunately got Mr Nob who said it was her problem and she would have to 'take her ex-boss to a tribunal' to get the money off him and then pay HMRC the tax bill. She then phoned me in a bit of a panic and I got her to speak to my accountant (no charge) who said that was nonsense and she should get back on to HMRC.
She then phoned HMRC again and this time fortunately got Mr Nice. She said firstly you've got all my payslips and secondly, if you received a letter in May 2023 saying I'd received a salary but the firm had made no deductions how come you didn't bill me back then. Mr Nice waffled about "these things are either done automatically or manually and if manually it may have been missed" but then said anyway we accept your evidence and you no longer owe us anything. I said did you get HMRC guy's name for reference and the answer was yes. She also checked on the app and she's all clear.
So it looks like HMRC will be after ex-boss for the money but will also be reported to the SRA. He'll probably just say it was an accounting error, cough up to HMRC and apologise to the SRA.
I said what about student loan and NEST deductions and apparently ex-boss actually did pass on the loan deductions (a miracle).
As for NEST, when she first joined the firm, a few of the staff checked their pension statements and saw that he had not been passing on the deductions. They confronted him back then and as a result the NEST contributions were up to date.
My original query was more: If a PAYE employer fails to pass on deductions then where is it written down who HMRC goes after? Is it the employer or the employee? In this case it seems that HMRC decided the employee was in the clear but what the actual legal basis for this is I don't know.
Sorry about all the boring detail but that's as clear as I can make it.
Thanks for all your contributions.