Hi,
As the payment is from your employer, the income should be shown in the employment section if it is included in your P60.
You would then claim credit for the Tax in the foreign section under 'Employment, self-employment and other income which you paid foreign tax on'. The foreign tax credit can be up to 100% of the foreign tax paid. You will need to amend your tax return.
If online, you add the foreign page and declare the tax in the foreign employment.
Alternatively, you can submit a paper SA106:
Self Assessment: Foreign (SA106) for the tax year in question, with a covering letter advising you are amending your tax return.
You have until 31 Janaury 2026 to amend your 2022-2023 tax return.
Thankyou.