Planning an international trip takes a lot of preparation: choosing the destination, buying tickets, getting the necessary documents… and making sure everything is in order before checking in. However, there are circumstances in which, after purchasing a flight, the information on your passport may have changed. One of the most sensitive cases is changing the gender marker.

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This change can occur for various reasons: a gender transition process, a correction of personal data in the civil registry, obtaining a passport with a non-binary “X” marker, or even administrative corrections. Although the legal validity of the passport itself is not compromised, the difference between the information in your booking and that in your document may raise questions about whether you’ll be allowed to fly, whether you’ll need to update your details, or whether you might face problems at immigration control.

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In recent years, several countries have adapted their policies to recognize gender markers other than the male/female binary, but the reality is that acceptance is not uniform. In addition, recent regulatory changes, such as those issued in the United

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States starting in 2025, have created uncertainty for travelers with documents that do not match the traditional format.  

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In this guide, we explain how this change can affect your travel plans, what authorities and airlines say, which countries accept different markers, and what steps you can take to make sure your trip goes smoothly.

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Legal framework and current situation

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In many countries, the passport remains valid until its expiration date, even if the gender marker does not match the sex assigned at birth. In the case of the United States, for example, the Department of State recognizes that a passport with an “X” marker or one updated after a gender change retains its legal validity, although in 2025 new rules came into effect limiting the issuance of passports with a non-binary marker or one different from that assigned at birth.

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In some European countries, such as Denmark or Ireland, warnings have been issued to citizens traveling to places where the acceptance of the “X” marker is not guaranteed, recommending that they verify requirements with the embassy before traveling. This is important because, even if your passport is valid in your country of issue, interoperability with foreign border control systems may not be guaranteed.

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Why can it affect your flight booking?

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When you buy a plane ticket, airlines request information that must match your travel document: name, date of birth, and, in some cases, gender marker. The main goal is to comply with security requirements and facilitate validation by immigration authorities.

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If the gender marker change in your passport happens after you’ve purchased the ticket, there could be a discrepancy between the information in your booking and in your updated document. While in most cases the gender marker is not a critical factor for boarding (as long as the name and date of birth match), on certain routes or in some check-in systems the difference may trigger additional verification or delays.

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What airlines say

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Most airlines prioritize having the name and date of birth match exactly with the passport. If the gender marker does not match, ground staff may conduct a manual check, especially if you’re traveling to a country with stricter immigration policies.

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Practical tips:

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• If your booking and your passport do not match in the gender marker, contact the airline as soon as possible to update the details.

• If the system does not allow an “X” or different marker, select the one that most closely matches your personal presentation to avoid questions.

• Keep copies of documentation supporting the change, in case you need to explain it during your trip.

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The international landscape: acceptance of the “X” marker

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Currently, only a limited number of countries officially recognize the “X” marker or non-binary gender categories in passports. These include Australia, Canada, Germany, and New Zealand. However, even in these cases, not all destination countries are prepared to process this type of document in their immigration systems.

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This means that if you travel with a passport containing an “X” marker, you might face additional questions at the border or be required to provide supplementary information. Keep in mind that acceptance is particularly variable in countries where gender identity laws are more restrictive.  

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Steps we recommend if you change your marker after booking a flight:

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• Check the validity of your passport: if your document is valid and current, you can travel, but research the destination country’s requirements.

• Contact the airline to verify whether it’s necessary to update the information in your booking.

• Carry supporting documentation (for example, official certificates of data changes or government statements on your passport’s validity).

• Check with the embassy or consulate of the country you’re traveling to, to confirm they will accept your document as is.

• Avoid last-minute changes to your passport before a trip unless strictly necessary, as some processes can cause delays in issuance or renewal.

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Changing the gender marker in your passport after booking a flight does not mean your trip is at risk, but it does require extra attention. Differences in international acceptance and updates in issuance policies can create uncertainty if you don’t act in advance, so make sure to verify destination requirements, inform the airline, and always have documentation proving your documents’ validity.

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Having everything prepared will greatly increase your chances of a smooth trip, allowing you to focus on what really matters: enjoying your destination!