Changed passport since obtaining Green Card - which do I use for application (N-400)

[sacredzero]

I gained unconditional GC in 2005 through marriage; came here as a South African citizen. I am no longer married and my GC is coming up for renewal in 2018 and I would prefer to apply for citizenship vs renewal. I am also a British Citizen through decent which I applied for and just received including my British Passport. My question is under which should I apply for my US Citizenship? I came here under South African, will it cause concern if I now state British Citizenship? Furthermore I am going on a trip to Europe soon and I know I have to state everywhere I have travelled so if I apply under South African but travel on British (as the SA passport is less than useless) is that a flag? Any guidance would be appreciated as I would like to apply soon. Oh as an aside, I will retain dual nationality, British and USA, I am relinquishing South African if that helps.

[NettieL]

I gained unconditional GC in 2005 through marriage; came here as a South African citizen. I am no longer married and my GC is coming up for renewal in 2018 and I would prefer to apply for citizenship vs renewal. I am also a British Citizen through decent which I applied for and just received including my British Passport. My question is under which should I apply for my US Citizenship? I came here under South African, will it cause concern if I now state British Citizenship? Furthermore I am going on a trip to Europe soon and I know I have to state everywhere I have travelled so if I apply under South African but travel on British (as the SA passport is less than useless) is that a flag? Any guidance would be appreciated as I would like to apply soon. Oh as an aside, I will retain dual nationality, British and USA, I am relinquishing South African if that helps.

You will be travelling as a South African born, British Citizen.

Your US Citizenship Application is a separate issue.

[newacct]

Your nationality is pretty much irrelevant in the naturalization process. For the purposes of answering Part 2 item 11, the N-400 instructions say "If you are a citizen or national of more than one country, type or print the name of the foreign country that issued your last passport."