Dual Citizen? What Passport to Use at the Airport

When I became a dual citizen of the US and Italy, I really didn't know when to use each passport at the airport. I often fan out the whole card deck of family passports in front of check-in agents and let them help me figure it out, but I've come to realize there's some simple tricks for fellow Americans traveling abroad to utilize if they are dual citizens. Here, I break down what I've learned.

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If you are an American with dual citizenship leaving the US on a trip, follow these general guidelines for which passport to use. Here, I use the EU as an example because I have dual citizenship with Italy (EU). (Learn how to get yours here!)

What Passport to Use at the Airport

Check In and Out of Countries Like a Hotel

When leaving the United States, you are effectively "checking out" of the country. You aren't actually passing through any customs controls, but they know you are leaving.

Think of it like a hotel.

• Check out of the US to go to the EU.

• Check into the EU.

• Check out of the EU to go to the US.

• Check into the US.

Here's the most basic breakdown I can try to make:

Outbound US to EU:

• Checking in for a flight: Either passport (typically whichever you applied to the check in profile)

• Boarding the plane: EU passport

• Arriving in Europe: EU passport

Inbound to US:

• Checking in for my return flight: U.S. passport ALWAYS

• Exiting Europe: EU passport

• Pre-flight passport check: U.S. passport ALWAYS

• Entering America: U.S. passport

Note: If you had used your EU passport they'd ask for an ESTA or VISA to enter the US

During Check in

During Check in Online

• If your final destination is in the EU, apply your EU passport information during check in.

• If your final destination is the US, apply your US passport information during check in.

If You Have a Connecting Flight

If you have a connecting flight to the EU that is within the US or EU:

Apply your EU passport information during check in.

If you have a connecting flight to the EU that is NOT within the EU (example, London):

• Apply your US passport information to your ticket arriving in London

• Apply your EU passport information to your ticket arriving in the EU

  
  

This applies only if you are ticketed for two separate airlines. (For example, fly to London on Norse Air and connect to Spain using Ryan Air). If you are ticketed through on the same airline, use your EU passport information inbound to the EU and US information outbound to the US.

If you ARE changing airlines, apply your US passport for the first flight (only if not an EU destination). This keeps things tidy, especially if you arriving in London where you have to have an ETA filled out for your arrival to the UK.

Special Note for UK Travel

All travelers going through the UK will require an ETA. The cost is 10GBP and it is valid for 2 years. Even EU Citizens require this ETA.

All applicants should apply at GOV.UK to avoid scam sites charging hefty fees. Install the ETA app in your Google Play or Apple Store and take care of this prior to stepping on your flights to the UK, typically at least 2 weeks in advance of your travel.

Passengers need the UK ETA even if just passing through, and you will need to sign up for the UK ETA with one passport or the other. I signed up for mine with my US passport, which means every time I step foot on UK soil, I've got to be an American.

This is important to note when carrying dual citizen passports. So to apply this to the above rules, you would travel US to UK using your US passport (in order to successfully arrive in the UK as an American). Then, you'd travel from the UK to Europe as an EU citizen. Remember the 'hotel check in' - check out of the UK as an American!

! ! Note: Starting 4th quarter 2026, all US citizens will be required to have an ETIAS (similar to an ESTA for Europeans entering the US). This form and fee must be filled out in advance of travel. If you are a dual citizen and have citizenship with the European Union, you DO NOT need an ETIAS to enter the EU. You can read more about this upcoming change here.

Have I Lost You Yet?

Let me recap:

There are three places you will be required to show your passport:

• Check-in (online or at the counter)

• Customs

• Boarding the plane

Check in can be complicated, but just remember it all hinges on your final destination. Use the passport associated to that country/region.

Customs serves to check you in and out of a country. Did you enter as an American? Leave as an American. Did you enter as an EU Citizen? Leave as an EU Citizen.

Boarding the plane - use the passport associated with the ticket (I.e., what you used at check-in).

When things get tricky - flash them all!

Yes, go ahead and flash everyone

When you arrive in Europe, pop that US passport in your bag, because from here until you leave, you are a European. Bypass crazy lines for foreigners and get straight to the front with your European passport. Just flash it around so all the Americans don't give you the hairy eyeball.

Other travelers will want to wring your neck when they hear your English and see you smiling and sauntering past what could be an hour long wait. They’ll probably mutter that you’re a stupid American and in the wrong line. Just keep flashing that passport and that smile, because you’ve got dual citizenship, baby!

Note that families traveling with children (typically 18 and under) cannot go through the turnstyle lanes that you may find at some customs facilities, and they will need to bypass the line anyway to a booth style customs agent. Flashing your EU passport is always the best bet, and someone will lead you to the correct line.

Dual Citizen Confusion In the airport

When you show your passport to people like at security, check in and even getting into the Priority Pass Lounge, keep whatever passport handy that is going to be the most useful for the situation. Lounges and duty free shops don’t really care, and at security, same thing. It’s just when the passport is being scanned for identity that you need to follow the above rules. 

I.e., checkin, boarding and customs.

For more information on obtaining your dual citizenship, consult the following resource:

My personal experience getting dual citizenship with Italy, along with step by step instructions.