UK entrance/exit with dual citizenship (UK and US) and ETA requirement

Hi Kerry. I am an EU/US citizen. I leave/enter the USA on my US passport and put my US passport number in my ticket. I enter/leave the EU on my EU passport. I only put my EU passport number in my airline ticket if I'm flying places that do not include the US. Hope this is helpful!

You need to have both passports with you. The US does not ask for a passport on exit, just for ID at TSA, and your airline will want to verify you have proper documentation. Since airlines now will kinda-sorta be required to verify the ETA, you should let them know you have a UK passport to prevent any issues.

Entering the UK, you must use your UK passport, no ETA required. While in the UK you are just a UK citizen. When you leave the UK, there likely will be no exit immigration. Once you land in the US, you must use your US passport to enter.

If you are going to one of the Schengen area countries on this trip, it really does not matter what passport you use.

I am a dual citizen as well, and do this regularly. When I book my flight to the US I use the passport info for my US passport and enter on my US passport. The only time it is checked is when I’m boarding the plane, the UK does not have immigration exit checks. Then when I fly home when I’m checking in online I change my passport info to my UK passport. Again there are no exit checks in the US so I just use my UK passport to board the plane and then to enter the UK. It’s pretty simple and I’ve never had an issue. Good luck, and happy to answer more questions if you have them!

Thank you all! It sounds like it's pretty straightforward, and that I'm unlikely to get into any trouble so long as I have both passports with. Much appreciated.

I have both a US and UK passport. I ended up just getting the ETA as I didn't want to have any problems when boarding my flight to the UK. I know you don't need it if you are a UK citizen or you can't supposedly get passed the one question on the form about dual passports, but I spent the $12 and have the ETA for 2 years. It came back within 5 minutes of applying. I travel to the UK 2-3 times a year, and haven't ever got in trouble for just traveling on my US passport but then I am only staying for 2-3 weeks at a time. I only enter the US passport into my flight details on my American Airline or Delta account. You don't have to show both passports when leaving, honestly most of it is biometrics facial recognition. Upon arrival in the UK, I use the e-gates with my US passport. I leave the UK on my US passport to match my flight details.

I find it more complicated to switch up passports in the midst of travel. I take my UK passport with me, but have only used it a handful of times when I have entered European countries from the UK.
. If I planned to stay longer in the UK than allowed on a US passport, then I would have to enter with my UK passport at Heathrow. You can choose to go to the UK line at Heathrow once you land if that is what you want to do, but I often have other people traveling with me that do not have dual passports and its just easy to go through the egates and stand in line with them.

Also, you have to enter the US on your US passport, and its got to match your airline. so that is why I always leave the UK on my US passport.

To clarify, the rules have recently changed about entering on a non UK passport if you are a dual citizen. See here: https://www.gov.uk/dual-citizenship

Copying the relevant text below:

"As a dual national, you must travel to the UK using either:
-a valid UK passport or Irish passport
-any other valid passport with a certificate of entitlement

You can apply for a passport or certificate of entitlement if you need one. You will not be able to travel without one of these documents.

You cannot get an electronic travel authorisation (ETA) if you’re a British or Irish dual citizen."

Therefore I do not recommend entering the UK on a non UK passport or applying for an ETA if you are a dual citizen. As I mentioned above it's quite straightforward to travel out on one passport and back on another.

Thanks for the clarification. I got the ETA when it first came out and it was not clear what dual passport holders should do and there was a "transitional period" to work out some of these issues.

I have not had any problems using my US passport to enter the UK for my past 4 visits. I know the US make it clear that all US citizens must use a valid US passport to enter and depart the United States with no exceptions, and this is where it gets confusing, as without the ETA, at some point you would have to produce your UK passport to show the airline that you can travel to the UK without the ETA.
I have a trip in March and I have an ETA that will expire January 2027. I will continue to use my US passport to leave and return to the US and enter the UK on my British passport. If I have any issues, I will come back to the forum to let you all know how it goes.

Following up on this- just announced: "Dual nationals to be denied entry to UK from 25 February unless they have British passport"
https://www.theguardian.com/politics/2026/feb/13/dual-nationals-denied-entry-to-uk-british-passport-border-control

If you are a UK citizen, you must enter the UK on your UK passport from 25 February. I believe an exception to this is dual UK/Irish nationals who can continue to enter the UK on their Irish passport.

The other major exception is if you have a certificate of entitlement related to the passport of your other nationality. Although in most circumstances this would not make much sense.

The certificate of entitlement costs over £500.

This is causing problems for many people who live in countries which don’t allow dual passports to be held. These people are British citizens living in eg Spain.

The main issue is the cost - actually having a CoE is quite convenient. I have one as I was born in a Commonwealth country toBritish parents. I was not eligible for citizenship as my mother is UK born and women were not able to pass on citizenship. That has since changed, but the cost of applying for citizenship is prohibitive, and it doesn't give me anything I dont already have - I can live and work, and even vote, in the UK.

As I have mentioned I have always just traveled to the UK on my US passport. I am heading over the pond in 10 days. I notice my Delta airline app has my US passport loaded and I have Global Entry. I do have an ETA from last year, when things were fuzzy about the rules. I have an up to date UK passport and so does my daughter - so all is good there. But, Delta has no way of entering another passport on their app. Also, it asks wether I have an ETA, I do, but I guess its now invalid. What am I suppose to do. Do I need to just enter my UK passport in the app? but then what about the return journey? It looks like I wont be able to do an on-line check in.

What am I suppose to do. Do I need to just enter my UK passport in the app? but then what about the return journey? It looks like I wont be able to do an on-line check in.

To a degree, Delta does not care what you enter for a passport, and it has nothing to do with what passport you use when you enter a country. The only thing they care about is if you have the documents to enter a country.

You should probably not check in online, or at least check in online if you wish, but go to the service counter when you get to the airport. Let them know you have a UK passport, they will note that, you are then fine.

With the ETA, or eventually the ETIAS for Schengen passports. if you are a dual citizen, you likely will need a manual document check, until airlines allow entering multiple passports.

On return, no problem, if asked, let them know you have a US passport, on return at immigration, show the US passport.

It really is not too difficult, just go with the flow, have both passports, if questioned, show them both and let them figure it out.

Thank you Paul - I figured I would have to check in at the desk. Just glad my UK passport was not expired!

Just to reinforce what was said above- it's absolutely fine to fly on a different passport than the one you booked your flight with (as long as it's for the same person and is valid for travel to your destination). I had experience with this recently when my husband and I travelled to China. We booked our flights using our UK passports but then found out later that Irish citizens don't need a visa to visit China. As my husband is also an Irish citizen he decided to travel on that passport to save the expense/hassle of the visa. When we showed up at Heathrow for our flight to Beijing we went to the check-in counter and they changed his passport info in the system- the whole thing took about one minute. So, no need to worry, you will be fine!