(a) UK. (b) Canada. (c) USA. (d) Other.
(a) UK and (b) USA.
I put Canada on the list for fun.
Listing the UK is obvious but also an assumption. We assume that the child will be born in the UK, but if for some reason it is not born there will be citizenship issues which lead to taxation issues to be addressed.
Listing the USA is less obvious but important. The USA taxes on citizenship. US citizenship can be obtained by two means: 1) being born in the USA 2) being a child of a US citizen. So if Meghan Markle is a US citizen then her children can also be US citizens and following that also be US tax payers.
Circling back to why I put Canada or Other on the list. Being born is not always planned, meaning that the time and place can be beyond the parents control. Following that thought if Meghan was not in in the UK or USA when the child was born what would happen? I predict firstly that a diplomatic challenge would happen then some logical solution that might have long term tax implications.
Let me explain with an example. Dutch Princess Margriet Francisca was born in Canada but because of an act of the government the room where the child was born was declared “extraterritorial” to ensure that the child would not be born a Canadian citizen and British subject.