Stock Options vested in the UK and exercised abroad

Hello, I lived in the UK from 2015 to 2018, after that I moved to Italy (where I'm still resident) working for a sister company (Italian company) and filled P85 in order to get the right tax calculation. In November 2023 I exercised some Stock Options that were partially vested while I was living in the UK and therefore the former employer withheld taxes and NI contributions treating the proceeds as regular income (as per regulation) and issued a payslip with all the details. Since the amount is below the allowance (not applied by the employer) and anyway the amount has also been fully taxed in Italy (where I am resident from a tax perspective), what is the exact process to claim a tax refund? Can also NI contributions be claimed back? Thank you

Hi AndreaC87.
Please refer to Tax on your UK income if you live abroad.
Thank you.