Dual citizenship, also known as multiple citizenship or dual nationality, means that a person is a citizen of two countries at the same time. Dual citizenship can happen automatically in certain circumstances (like when a child is born to foreign parents in the United States, and the child therefore becomes a citizen of the U.S. and the parents’ home nation).

Likewise, if a child has parents that are U.S. citizens but is born overseas, she may automatically become a citizen of both the U.S. and the foreign country.
 
One can also apply for dual citizenship. If a foreign national has permanent residency in the United States (for example, if they have a green card) for at least three years and has been married to a U.S. citizen, she may be able to apply for dual citizenship through a legal process.

What Countries Allow Dual Citizenship?

The United States does not necessarily encourage dual citizenship, but it allows one the right to retain dual citizenship if you have been a dual citizen from birth or childhood, or you became a citizen of another country after already having U.S. citizenship.
 
There are a number of countries that allow dual citizenship (such as Germany, South Africa, Portugal, and Turkey, to name a few) and many that do not allow dual citizenship (such as Austria, Indonesia, Ecuador, and Venezuela).

Further, there are some countries that only allow dual citizenship with specific countries. For example, Spain allows dual citizenship with some Latin-American countries, but does not allow dual citizenship with the United States.

What Precautions Should I Take Before Traveling as a Dual Citizen?

First, check your dual citizenship status. While you may have filed appropriate paperwork for dual citizenship, it may not have been processed or filled out correctly. In that case, you may not be a dual citizen, and travel would be more straightforward.
 
If you do in fact hold dual citizenship and plan to travel, contact the nearest diplomatic office of the country where you intend to travel to find out whether there are specific requirements that you need to meet.

What Passport Should I Carry When I Travel?

If your travel destination is your other country of citizenship, travel with both your U.S. and destination’s passports. When showing your documentation to airline officials, it’s best to show the same documents as what you show immigration officials as well as your U.S. passport. U.S. law requires its citizens to be in possession of a U.S. passport or other proof of citizenship when leaving the country.

What If I Left My Country Under Less Than Friendly Terms?

If this is the case, exercise caution when you travel near that country, over its airspace or through its territorial waters. You should also be careful traveling to or near at third country that has an extradition treaty with your old country.

Do I Need an Immigration Attorney?

Dual citizenship and traveling as a dual citizen are complex issues that have specific legal obligations. For this reason, it’s a good idea to seek counsel from a skilled immigration attorney to advise you on citizenship matters and assist you in the event that any complications arise.