Working for overseas employer for the first month that I came to the UK. Do I need to pay NI?

Hi Admin, for the first month when I has just arrived UK, I was still under the employment contract with my HK employer that has no presence in the UK and has no business in UK. During that month, I was staying in an Airbnb room. The contract was changed to self-employment contract after that month with no basic salary and no benefit. I saw a thread before saying that in this case, one just need to file a self-assessment form so I reported the employed and self-employed incomes in a self-assessment form. But recently, I have heard someone saying that I need to pay NI for that month's income that I earned under the employment contract. Do I need to pay UK NI for that month? If yes, how should I do this? Many thanks in advance.

Hi,

Income arising from employment in Hong Kong, while resident there, is not taxable in the UK and should only be shown as additional information in box 19.  

It is not subject to National Insurance.

Thank you.