Foreign income one-off back pay

Hi HMRC Admin, I arrived in the UK on 1 July 2022 and become UK tax resident for the year 2022-2023. My last working day in HK is 3 June 2022 and received a one-off back pay salary GBP250 from HK employer for the period 1 Apr - 3 Jun 2022 and credited to my account on 1 Aug 2022. I have a UK full time job started from 20 Oct 2022 until end of the tax year 2022-2023. Do I need to submit the self assessment and report my Hong Kong one-off back pay salary GBP250 to HMRC? If yes, I'll fill in the SA109 to apply split tax treatment. Then -on the SA100, page TR2 should i put "X" in "Yes" box "I EMPLOYMENT" or "5 Foreign"

Hi Noelmaru,
Your back pay is not taxable in the UK under the DTA as the work that it relates to was carried out in Hong Kong.
Thank you. 

I arrived in the UK on 1 July 2022 and signed half year rental agreement with landlord for the period of 1 July - 31 Dec 2022. And then moved to a house at the end of Dec 2022. May I know when is the exact date that I become the tax residence in the UK? thank you.

Hi Noelmaru Cheng,
That is for you to determine based on the guidance available.
Please refer to:
RDRM12000 - Residence: The SRT: Split year treatment: Contents
Thank you.