Just signed up and this is my first question.
I have recently become a citizen of Australia and will be traveling back to the US again soon. I already have an ESTA on my European passport however now that I am Australian too I have to use this passport when traveling in and out of Australia (this is apparently mandatory for AUS immigration). Do I have to apply for a new ESTA on my Australian passport to now travel to the US or can I use my existing one on my EU passport? Am I able to check in with the airline when leaving Australia on my EU passport but then show my AUS passport at Immigration when exiting the country and then show my EU passport when landing in the US? Or do I need to use the same passport for both?
There seems to be conflicting info online. A similar question was already asked on here but the only answer to that did not offer clear explanation. My question also refers to checking in with the airline on one passport and showing immigration another passport and whether that is ok or not.
