Foreign tax taken from UK PAYE during work abroad

Hello I was trying to research this but most of the information seems to be a bit vague/I'm unsure what would apply to me. Last year, between July and November, I was sent abroad for work (Hungary). I was engaged as PAYE. I had Hungarian tax deducted from my payslips (15% on all income) - which came off the UK tax (ie. if £200 UK tax was due in total, the payslip had £50 UK tax and £150 Hu tax). My new employer (started December, back in the UK) actioned my P45 and the week after I've been issued with a K3718 tax code. After calling the personal tax helpline, I've been put back to a regular 1257L wk1 code, which I am still on, however I've been notified that for the next tax year I'll again be on a K tax code. As there's meant to be a taxation treaty with Hungary - how am I meant to go about this? I have paid the taxes due, just in a different country. Is this something my employer should have been reporting? Should I be doing a self assessment for the foreign tax paid? Any advice would be welcome, as I'm just quite anxious about this now. Thanks

Hi David,

Please refer to guidance at Tax on foreign income

Thank you.