Could really use advice. For a few years DH was self employed and as a result filled in a self assessment tax return. All fine - though in 2022 he became a full time paid employee of a big US company who operate payroll out of the US, but use a remote company to process the payments to European employees in their native currencies.
At some point after a few months of working for them, DH's tax code was changed, and in February of this year he received a bigger than usual salary payment that month. He flagged this to his company, and was told that this was a result of him being on the wrong tax code previously, and was a rebate.
Yesterday DH went to submit his online tax return, fully expecting to state that there was nothing to declare as he's an employee on PAYE. He was shocked to see that HMRC are saying he owes 7k - and this calculation seems to tie in to the 'rebate' somehow. Although it looked like he was paying the correct amount of tax each month - the payments didn't change after February, it appears as though he hasn't paid enough tax across the year - and now owes this amount.
Am I correct in thinking that if this is the US employer's cock up (or indeed HMRC's cock up for changing the code), it's not up to DH to pay it?! We don't have 7k to pay them for a start. Anyone experienced similar and what did you do?