UKMoveE24

I am writing to understand if I will need to pay NI under the following circumstances: 1. US Citizen in the UK for >6 months as a dependent on a SW visa and paid the IHS as part of that visa application 2. I am working for a US company with no presence in the UK and am getting paid exclusively in USD in a US bank account 3. I will be a non-domiciled UK resident for UK Taxes 4. A portion of every US paycheck is being withheld for US Social Security Will I have to pay/be liable for national insurance if I am already having a portion of my pay withheld for US social security (in my understanding, the US equivalent of NI)? Please let me know if I am misunderstanding any aspects. Thank you!