Saving interest, split year treatment & cancel self assessment

Hi Admin I was aboard UK in 10/2023 from Hong Kong through BNO Visa. I checked I am a UK resident by residence status tests, but am unemployed & have no incomes in UK. I have registered self-assessment to HMRC for my incomes from Hong Kong personal bank accounts interest and dividends interest throughout 23/24 tax year, Please my questions are: I don’t understand which period i should declare the above interest incomes : 23/24 whole tax years or only UK parts after aboard as below： A) If answer is 23/24 whole tax year (the both above incomes received are more than £10,000), am I correct what I should take the split year treatment to declare 23/24 whole years if I am qualified? B) if answer is UK parts (but the both above incomes received less than £10,000), is self-assessment no longer required? If yes, Can I go to cancel and how to cancel self assessment as I have registered self assessment in error? Thank you very much.

Hi,
As you have confirmed that you are tax resident in the UK for the whole of tax year April 23 to April 24, you will need to determine whether you qualify for split year treatment, by reviewing the guidance and taking the tests at RDR3 Statutory Residence Test.  
If split year treatment applies, you declare this in your tax return (SA109) and you declare in the tax return all of your UK income for the whole tax year and your foreign income only from the date you arrived in the UK to the end of the tax year.  
If split year treatment does not apply, then you have to declare your world-wide income for the whole tax year in the tax return and claim a foreign tax credit for overseas tax paid.
Thank you.