HK Previous Salary, Contract Gratuity and MPF

Good Morning, My family immigrated to the UK from Hong Kong in July 2023. Before that, I was employed as a contract staff in Hong Kong and I would have a “contract-end gratuity” after finishing the 3-year contract on 31 Aug 2023. Because of the remaining annual leave, my employer agreed to end my work and leave on 15 July 2023. (as taking the annual leave from 15 July 2023 to 31 Aug 2023) However, the salary was paid as per the original schedule. I arrived in the UK on 20 Jul 2023 from Hong Kong, and my UK house rental started on 01 June 2023. I will apply for the split-year treatment for the tax return 2023-24. I would like to clarify whether the following items are taxable or “not taxable but need to report/declare on SA110/SA109“ for the self-assessment tax return. 1) The Hong Kong salary before 20 Jul 2023 (Do I need to report/declare it?) 2) The money paid for my annual leave from 21 Jul to 31 Aug 2023. The money was received on 31 Jul and 31 Aug 2023. (Is it taxable in the UK? If not, do I need to report/declare them as well?) 3) The “contract-end gratuity” I received on 31 Aug 2023. (Is it taxable in the UK? If not, do I need to report/declare them as well?) 4) Also, do the items 2 & 3 need to pay the NI? 5) I also received the HK Mandatory Provident Fund (MPF) in Oct 2023 related to my previous employment. It should be nontaxable as it is eligible for the double tax agreement between HK and the UK. Anyway, do I need to report/declare them, and which SA (SA109?) form should be used? Thank you very much for your concern and advice

Hi,
Although this Hong Kong employment and bonus income were paid when you had arived in the UK, the tax treaty confirms that it is only taxable in Hong Kong.  
If split year treatment applies to your circumstances, you would only need to mention the income in the freehand box 19 on page TR7 of SA100.  
It should not be declared anywhere else. Any income that is not taxable in the UK, should be shown in the additional information box.  
In this way you are complying with the requirement of full disclosure, but will not be including in any calculations.  NIC is not chargeable on non taxable income.
Thank you.

Thank you so much for your information :)