Hi Ed Leung,
Overseas dividends should be declared in a Self Assessment tax return, regardless of how much they are.
You can enter the dividends in boxes 5 and 6 of SA100, provided the guidance those boxes can be applied.
If not, they must be declated in SA106.
Self assessment will apply the tax free allowance in the calculation.
Have a look at the notes on page TRG6 for boxes 5 and 6.
Tax Return notes Tax year 6 April 2023 to 5 April 2024 (2023
Under the terms of Self Assessment, we do not provide an official exchange rate and the onus is on the individual to use a just and reasonable exchange rate for each acquisition and disposal.
For your convenience, there are exchange rates here:
Exchange rates from HMRC in CSV and XML format
For older rates here:
Exchange rates.
You are free to use any of the supplied rates or one of your own choosing.
Thank you.