Thanks for your reply and for the link to the relevant info. To clarify - does the 'overpayment relief' claim apply to underpayment of tax cases? I actually owe tax to HMRC as I deducted the full amount of foreign withheld tax from my total tax liability, so the refunded amount is what I'll have to pay to HMRC for both 2019 and 2020. I am not claiming an overpayment of tax.
I am a UK tax resident, use cash basis accounting, have trading/employment/investment income.
My salary came from foreign employment and was taxed at source in the foreign country in 2019, 2020. I claimed FTCR as per the DTA for these on my UK tax returns.
In 2023 I unexpectedly found that I was due a refund of some of that withheld foreign tax.
The deadline to amend my 2019 and 2020 UK returns has now lapsed, do I add this refund to my current return? Do I report amounts due (as per the calculation on the foreign tax return) or the actual received refunds, foreign tax returns were submitted late and there is no guarantee I will get a full refund due to timing.
Also will I have to pay a penalty + interests calculated from 2019, 2020 for the respective due/refunded tax amounts?
Can you please provide me with a link to a related guidance/legislation.