Self Assessment Registration and Exchange Rate

Background: I moved to UK in 2022/23 and I was not employed for the year but only earned overseas saving interest for ~£300 depending on the exchange rate. I tried to registered for Self Assessment on 4 October 2023 but have no idea why it was halved and no UTR or any confirmation received. I called to hotline on 5 October 2023 since I concerned if the interest earned is required / up to the required amount to file Self Assessment for 2022/23. The HMRC representative walked me through a series of questions and confirmed that I am not required to report or registered Self Assessment. I worked in 2023/24 for 6 months and employer has already filed and withheld tax via PAYE. I heard from various sources recently so checked on this Community Forum to find out that regardless how much is the overseas income including saving interest and if that fund remitted to UK or not, I am required to file via Self Assessment. Question: 1. How can I generate Self Assessment? Request paper form, register online like the failed attempt did in 2022/23 or via my Gateway account? 2. How can I report the ‘potential’ missing Self Assessment for 2022/23? 3. Once I successfully register the Self Assessment, how can I also file for 2023/24 overseas interest on top of my PAYE since I already received Tax Calculation for 2023/24 with refund? 4. Interests are credited to my overseas bank accounts on monthly basis but I did not remit to UK so far. When I file the amount of overseas interests, which exchange rate should I use, spot rate on the date interest credited (not found on Gov.uk) or monthly average or yearly average wage as of 31st March of relevant years?

Hi Pamela,
The default method for calculating tax in the UK is the 'arising' method.  Tax is payable on income or capital gains in the tax year it arises, whether from the UK or world-wide.
A self assessment tax return is required where there is foreign income.  The exemption from small amounts of foreign income, described at point 9.12 is limited to £100 of foreign bank interest. (Guidance note for residence, domicile and the remittance basis: RDR1).  
As you exceed this amount, you will need to declare the interest in a self assessment tax return.  You can register for self assessment at:
Register for Self Assessment if you are not self-employed, either online or by printing and posting the form.  
You can download the paper version of the tax return and supplementary pages at: Self Assessment tax return forms  
If you choose to claim the remittance basis, this must be done on a tax return. Self assessment does not state which rate of conversion you must use. Self assessment advises that a just and reasonable exchange rate is used. For your convenience, you can use any of the rates provided by HMRC or for another source of your choosing.
Thank you.

Thank you, HMRC team. I already registered for Self Assessment per above instruction a week ago. May I know when I can have my UTR in my Gateway account or receive letter for such information? Before I received the UTR, does it mean that I cannot file the Self Assessment Form to report my overseas income online? Thanks

Hi Pamela Chan,
After registering, you should receive confirmation of your UTR in the post in 3-4 weeks.
If your abroad, it can take two months.
You do need to receive your UTR before you can file a tax return. 
Thank you. 
 

I still did not receive any letter for UTR. Try to call 0300 200 3310 but it keeps asking me to tell the reason for calling for many time but in return the answer given was totally not relevant or not helpful. In any other way, I can reach anyone to advise my status. This is the second year, I found challenges to complete the process.