My kids are dual Danish and US citizens. My husband and I are permanent US residents, our kids being born here.

When we travel back and forth between Denmark and the US, we have been solely using the kids US passports.

Obviously, for entry into the US (and check in at the airport) they need to use their US passport, as they have no visa.

On arriving in Denmark, they have a automatic 90 day travel visa, so just showing the US passport have been enough.

There are a couple of other questions around this I explored on the site: Travelling with two different passports, Traveling with two passports which one to use and more, and all of them state that you have to use the passport of the country you enter if you hold that passport, and that in some cases you are required to.

However, we have not been doing this for kids, as I heard anecdotally that it can cause trouble when entering the US. A friend of mine with dual US/other citizen ship used his other passport when entering that country, and at some point he was asked on US re-entry where he had been, and why he had no stamps in his passport. He was told by the US immigration officer that you have to use the same passport for your entire travel.

Is this correct? Or should I use my kids Danish passports for entering Denmark?

  • Technically, what they get upon arrival in Denmark isn't a visa, it's just an entry stamp.
    – Relaxed
    Jul 1, 2014 at 23:32
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    To avoid any potential problems, all you need to do is present the same passport at the same customs checkpoint. This will provide a complete record of arrival and departure, whereas using one passport for arrival and one for departure just leads to potential confusion or inconvenience. Which passport you use at which customs checkpoint depends on your circumstances and the regulations you want to follow. Jul 2, 2014 at 1:47
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    I don't believe you show passports to customs when you leave the US (or Denmark). You show them to the airline, so they know you will not be turned back. You show them to the TSA (or similar) to verify ID in the airport. But neither of those places do they check stamps.
    – Ida
    Jul 2, 2014 at 3:59
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    @Ida There is no exit check in the US (but the airline have to share your passport details with the US authorities) but you should have to show your passport when leaving Denmark and many other places.
    – Relaxed
    Jul 2, 2014 at 5:50
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    A US border officer also told my sister that dual nationality is unconstitutional. But prohibitions against dual nationality are unconstitutional (see en.wikipedia.org/wiki/Afroyim_v._Rusk). Don't believe everything you hear from immigration officers. If Denmark had a law (as the US does) requiring Danes to use Danish passports on entry, you would then be required not to use the same passport for an entire trip. I am Dutch/US dual. I show my NL passport to EU officials and US passport to US officials. Airlines get the NL passport when I fly to the EU and the US when I fly to the US.
    – phoog
    Aug 18, 2014 at 23:25

2 Answers 2


The general rule is that you should always use the country's passport when entering the country. As the other answers note, many countries (eg. the US) also have legislation requiring citizens to use their passport to enter/leave, although obviously this is hard to enforce.

Obviously there are cases where you can get away with this in practice, eg. your US/Denmark scenario. But what if, for example, one of you gets sick and you all have to stay in Denmark for over 90 days? Immigration's records will now indicate that the holder of that passport, an American citizen, has illegally overstayed, and you'll have a mess on your hands that you will need to sort out when you leave or next re-enter the country on that passport. Now, since your children are actually Danish citizens, I'm fairly sure this can be sorted out... but if you had just used a Danish passport to enter, you wouldn't have the problem in the first place.

And yes, your US immigration officer is full of poop. You do have to use a US passport to enter the US, so your friend was wrong in using his other passport for this, but what passport you choose to use outside the US is none of his business.

Update: Reworded to use slightly less loaded language per the comments.

  • thank you for clarifying. My friend was using his US passport in the US, but was told he had to use it abroad too.
    – Ida
    Jul 1, 2014 at 22:50
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    I honestly doubt, that you as a Danish citizen will be considered an illegal immigrant when staying more than 90 days in Denmark after entering with an alien passport. Jul 1, 2014 at 22:55
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    The kids are Danish citizens, they can't possibly be illegal immigrants. Using a given passport when entering the country might or might not be an offense but it does not change your citizenship.
    – Relaxed
    Jul 1, 2014 at 23:10
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    @jpatokal Except that the Schengen visa system does not work that way: There is no Schengen-wide database of entries or list of people who appear to have overstayed, enforcement is based on the stamps in the passport. If you show your US passport with an old entry stamp, you will have some explaining to do (i.e. show your Danish passport) but the talk about “illegal immigrant” still doesn't make much sense.
    – Relaxed
    Jul 2, 2014 at 5:44
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    @Relaxed I think jpatokal's allusion to "mess to sort out" means to wade through the bureaucratic horror that most people imagine would arise in this situation, to "get the kids' status in the database changed" or what not. My mother's experience as an American who routinely "overstays" in France (she's married to an EU citizen) suggests that in fact there would be no such horror. On leaving, the kids would be threatened with a fine; they'd say, "we're Danish but don't have passports," and they would likely be sent on their way.
    – phoog
    May 4, 2015 at 17:32

Each country is basically free to set their own rules. Generally speaking, presenting the local passport when you are a citizen is the most practical course of action but it's not like it would be some sort of overarching principle that applies to all countries in the world.

In all likelihood, Denmark does not care either way. The US, on the other hand, does make it mandatory to enter with your US passport if you are a citizen. In practice, doing what you have been doing therefore seems like a good solution. The only thing that could create problems is staying in Denmark for more than 90 days. US citizens who are not also Danish citizens would be liable for a fine if the border guards notice it when leaving Denmark (by checking the entry stamp). Producing the Danish passport at this stage should avoid any serious consequences but you can expect some confusion or complaints from the border guards.

I also seem to recall it's mandatory to present the same passport to the airline (airlines share data with the US government for all legs of your trip to or from the US) but I can't find a reference for that at the moment. To satisfy this requirement and still use your Danish passport in Denmark, you would need to show your kids' US passports at the check-in desk (and make sure that's the one the airline is recording in their system) and then the Danish passports at the police passport check.

  • You need to show your US passport or other proof of being able to legally stay in the US (such as green cards) when you check in. It has been a while, but I think you have to have a return ticket or at least an ESTA confirmation if you are not a resident?
    – Ida
    Jul 1, 2014 at 23:47
  • @Ida Yes, that's correct.
    – Relaxed
    Jul 2, 2014 at 5:46
  • @Relaxed Not if you're Canadian.
    – phoog
    May 4, 2015 at 17:27

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