The base rule
When you hold two nationalities, no country recognises your “other” nationality on its territory: if you are its national, it treats you as one, full stop. Everything else follows from that. The practical question is not “which is better” but which document to present at each specific check on a trip.
Carrying both passports valid solves almost every case. Problems appear when one is expired, or when the ticket was booked with the details of the wrong passport.
Entering and leaving the EU / Schengen
If you hold the nationality of an EU Member State (or Iceland, Liechtenstein, Norway or Switzerland), travel on that passport or identity card. As a Union citizen you have the right of free movement: the 90/180 limit does not apply to you, nor does ETIAS, nor the EES registration, nor passport stamping, and the entry check is the EU-citizen one, not the visitor one.
Two conditions that get overlooked:
- The document has to be valid. Directive 2004/38/EC recognises the right to leave and enter “with a valid identity card or passport”; a nationality certificate, a birth certificate, or citizenship “in progress” do not work at the border.
- Member States may not impose an exit visa or equivalent requirement on their citizens (Article 4 of the same Directive).
If you enter the Schengen area on your non-EU passport even though you are entitled to an EU nationality, you count as a visitor: the stay limit and the entry checks apply.
Leaving your country of origin
Many countries require their nationals to enter and leave on the national passport, even if they hold another nationality:
- United States. The law (8 U.S.C. § 1185(b)) provides that “it shall be unlawful for any citizen of the United States to depart from or enter … the United States unless he bears a valid United States passport”. A U.S. citizen with dual nationality must enter and leave the U.S. on the U.S. passport.
- Mexico. The Nationality Law (Article 12) requires Mexicans who also hold another nationality to present themselves as Mexicans before any authority on national territory, which in practice means entering and leaving the country on a Mexican passport.
- Other Latin American countries have similar rules; check the official immigration website of your country of origin.
The consequence: on a trip between your country of origin and the EU with dual nationality, the usual pattern is to leave the country of origin on that country’s passport and enter the EU on the EU passport (and the reverse on the way back).
The airline’s check
Before every international flight, the airline checks at the desk, through systems such as IATA’s Timatic, that the passenger can enter the destination country on the document presented. If you cannot show that, it can deny boarding, because the carrier is liable for repatriation and for fines if you are refused on arrival.
So:
- Book the ticket with the details of the passport you will use to enter the destination. Flying to the EU and entering as a Union citizen: book with the EU passport; flying to your country of origin: with the origin one.
- If, when booking, you already know you will clear a check with the other passport during a layover or transit, carry both and say so at the desk. Ground staff are used to dual nationals, but they need to see the document that justifies each leg.
Layovers and transit
On a layover within the same area (for example, two flights inside Schengen) the check happens once, on entry. On a layover that changes zone (for example, a flight to the U.S. with a connection) there may be an intermediate check: see the airport transit guide and, where relevant, the one on electronic authorisations.
Travelling to a third country
When the destination is neither of your two countries, present the passport that gives you the better entry treatment: the one that needs no visa, or the one with a simpler electronic authorisation. For instance, on a Spanish passport you enter visa-free into many countries that require a visa from other nationalities. Check each combination on your passport-and-destination page and travel on the passport you used to book the ticket to that country.
Minors with dual nationality
Some countries require minors to leave their territory with exit authorisation from both parents, or on the national passport. If the minor has two nationalities, check the country of origin’s exit rules before buying the tickets, not at the airport.
Frequently asked questions
I hold a Spanish and an Italian passport and I’m going to Spain. Which do I enter on? Either valid one: both are EU and give you free movement. It doesn’t matter which, as long as it is valid.
I’m Argentine and Spanish, but my Spanish passport is expired. Do I enter on the Argentine one? You would enter as a non-EU visitor, with the 90/180 limit and the corresponding entry check. To enter as a Union citizen you need a valid Spanish passport; renew it before travelling. We cover this in the corridor pages, for example Argentina → Spain.
Can I show one passport on exit and another on arrival? Yes, that is normal with dual nationality: you leave your country of origin on its passport and enter the EU on the EU one. Carry both, and if the ticket is in one name only, have the other to hand in case the desk asks to see it.
Does dual nationality spare me ETIAS or the EES registration? Only if you travel on the passport of an EU/EEA/Switzerland country. On that document, neither ETIAS nor the EES applies. On the non-EU passport, they do.
Guide verified 10/09/2026. Sources: Directive 2004/38/EC (free movement), Articles 4 and 5 (right of exit and entry with a valid identity card or passport; prohibition of exit visas for Union citizens); Regulation (EU) 2016/399 (Schengen Borders Code), Article 6; 8 U.S.C. § 1185(b) (requirement to bear a valid U.S. passport to enter and leave the U.S.); Mexico’s Nationality Law, Article 12. The airline’s document check relies on IATA’s Timatic database. Check your country of origin’s exit rules on its official immigration website.