For those who are not familiar about non-dom, this will make it clear.
What is ‘Non-Domicile’
If an individual is ‘non-domicile’ or ‘non-dom’, this simply means that they consider (and have declared) their permanent home to be outside of the country they are currently in, even if they live in that secondary country all year round. While this may sound fairly modern, it was first introduced in the UK in 1799 under King George III, and remains frequently used.
Mrs Murty has a domicile of origin of India. Although she is also an Indian citizen, these are two distinct concepts, and her citizenship is not directly relevant to the question of domicile.
Mrs Murty married Mr Sunak in 2009, and moved to the UK in 2015. Under current UK tax law she will be deemed domiciled in 2030, if she continues to live in the UK permanently. However, for the moment, despite being married to the UK Chancellor of the Exchequer and living at 11 Downing Street, Mrs Murty asserts that she does not satisfy the requirements to gain a new ‘domicile of choice’ of the UK. This is because this intention to reside in the UK (which forms a key condition of claiming a new domicile) must be an intention for the UK to become the individual’s chief residence, permanently and indefinitely. Mr Sunak has commented that his wife cannot satisfy this requirement, as she has an intention to eventually return to India to care for her aging parents.
I mean can you imagine those poor billionaire parents, how on earth will they be looked after? I ask you.
https://www.thorntons-law.co.uk/knowledge/what-does-non-domicile-mean