Dual Citizen which passport and when

Posted by helenbadstein on 08/20/26 02:49 PM

I am a UK US dual citizen. I have not traveled back to the UK since the UK immigration changes.
I have a UK passport and a US passport, but I am unsure which passport to use and when. Traveling alone and I am worried about having issues! I know that I can’t obtain an ETA as a British Citizen.

Which passport information do I use when I book my airline ticket?
Which passport do I use when I check in at the US airport?
Which passport do I use at the UK immigration on arrival in the UK?
Which passport do I use when checking in to leave the UK?
Which passport do I use when I arrive back in the US at the US immigration?

Posted by Laura

Virginia, USA

08/20/26 02:56 PM

6851 posts

You always use the UK passport when you are entering the UK.
You always use the US passport when you are entering the US.

For the airline, put your UK passport in when you are flying to the UK; show your UK passport at check-in.
Before you return back to the US, you can update your passport information on the airline website with your US passport. Show your US passport at check-in.

Posted by helenbadstein OP

08/20/26 03:06 PM

3 posts

Thank you for the information.

Posted by Paul

Eastern Iowa, USA

08/20/26 03:52 PM

9583 posts

Probably worth noting that entering the UK on your UK passport, and entering the US on your US passport is not optional, but a requirement.

As for what passport appears on your ticket, that really is not on issue, except in leaving the US, if your US passport is linked to the ticket, they likely will ask about an ETA, so just show them your UK passport. Same on return, if your UK passport happens to be on the ticket, you may get asked about an ESTA, again, simply show your US passport and all is good. Airlines are used to working with dual citizens, their only concern is that you have the right documentation..

Posted by helenbadstein OP

08/20/26 07:16 PM

3 posts

Thank you, appreciate your help.

Posted by lizzy.tilley

08/24/26 01:55 AM

42 posts

Do what Laura above says. I am a dual Canadian/UK citizen and did a 2.5 week trip to the UK in July. Flying over I put my details into my booking for my airline and presented my UK passport at the airport when checking in/dropping bags off. Presented UK passport at UK Immigration (often the e-gates at major airports such as Heathrow). Once in the UK, I went in to my booking for my return flight and changed my passport details to my Canadian one. Repeated above steps with Canadian passport at Heathrow upon my return. IF you haven't used the e-gates before, there are videos on YouTube that can make the process smoother. I had no issues or questions.

You use the passport for the country you are entering (UK for UK and US for US).