Questions about Split Year Treatment and Self Assessment

Dear Officer, Hello ! I would like to ask few questions about Split Year Treatment & Self Assessment. I arrived in the UK in October 2023 on a BNO visa. From April to August 2023, I had a full-time job in my home city, Hong Kong, and I have already settled my taxes there. I have been working in the UK from December 2023 to May 2024 and from September 2024 to now. I would like to ask: 1. Do I need to do a Self Assessment? When I completed the Self Assessment questionnaire, it said I didn't need to, but I have some overseas interest income. Even if it doesn’t exceed the tax-free allowance, do I still need to do a Self Assessment? 2. Do I need to apply for Split Year Treatment? 3. I applied for a UTR in August 2024, but I haven’t received it yet. If I don’t get the UTR in time to apply for Split Year Treatment by the October deadline, will I have to pay UK taxes on my income from my job in Hong Kong from April to August 2023, even though I have already paid taxes on it in Hong Kong? 4. Can Split Year Treatment only be submitted in paper form by October, or can I use software to submit it? 5. If I end up not being able to apply for Split Year Treatment before October because I haven’t received my UTR, and I have to pay UK tax again on income earned in Hong Kong before applying for a BNO visa (which I have already paid tax on in Hong Kong), can I apply for a refund from HMRC once I get my UTR? Thank you very much!

Hi David,
If you qualify for split year then you only report any foreign income for the UK part of the year: Residence, Domicile and Remittance Basis Manual.
If you do not qualify then you will need to report all your foreign income to the UK Tax on foreign income.
The guidance at RDRM12150 - Residence: The SRT: Split year treatment: Case 4: Starting to have a home in the UK only at www.gov.ukwill help you work out if split year treatment applies.
Thank you.