Hey Travellers

I travel on my UK passport but gained NZ citizenship last year. On my last trip to the US I had some trouble at the checkin since I didnt have the "citizen" endorsement in my UK passport (and didnt have my NZ passport yet).

Anyhoo, Im off to the US again in March.

Now that I have my NZ passport I was going to enter the US on my UK passport as I have a business visa in that passport.

Ive checked the NZ immigration site and it states that there are no issues travelling on multiple passports as long as you leave/enter NZ on the same passport (so that they can see you return).

The NZ side is pretty clear; exit on NZ and enter on NZ, all electronic so no issues.

What Im not sure about is on the US side. Obviously when you enter you get a physical stamp in the passport but I dont see any exit stamps in my passports.

So...

Do I check in at the US with my NZ passport or UK passport?

Do TSA simply check the name matches a passport or do they check the passport number?

Im guessing I need to check in with the UK passport but show them my NZ passport?