U.S. Customs and Border Protection (CBP has announced plans for changes to its procedures for processing information sent to CBP by airlines (and possibly also train, bus, and ferry operators) about passengers on international routes with non-binary or non-gendered “X” gender marker passports, to take effect on Tuesday, October 12, 2025.

The planned changes were disclosed by press release rather than by rulemaking notice in the Federal Register. Implementation has been outsourced to airlines subject to secret “Security Directives” from CBP.  Neither the current nor the planned procedures comply with the law. All of this makes it difficult to predict what will happen to anyone with an “X” gender marker on their passport who tries to make reservations, buy tickets, or check in for international flights after October 12th.

But here’s what we know:

Since 2005, CBP has required all airlines serving or overflying the US to collect and transmit to CBP, before each flight, information about each passenger. (Airlines are compensated by being given a free ride to retain, use, sell, or share this information for their own purposes.)

In 2007, this Advance Passenger Information System (APIS) was transformed from a purely informational (i.e. surveillance) system into a prior-restraint travel permission regime. Airlines were forbidden to issue a boarding pass or allow a passenger to board unless and until, after sending APIS information to CBP, they received an individualized, affirmative,  per-passenger, per-flight permission message. Airlines had to spend several billion dollars modifying their reservation and departure control systems to  require these Boarding Pass Printing Result (BPPR) messages from CBP before boarding passes could be issued.

Formats for the inclusion of APIS data in passenger name records (PNRs) were added to the ATA/IATA Reservations Interline Message Protocol (AIRIMP) in 2004 , and since 2006 all ATA and IATA member airlines have been required to accept AIRIMP messages with APIS data.

The AIRIMP formats implemented by airlines and computerized reservation systems (CRSs) initially allowed a gender code of “U” (“undisclosed”) as an alternative to “F” or “M”.

But the APIS regulations promulgated by CBP in 2005 explicitly required either “F” or “M”. In accordance with these regulations, CBP’s APIS guide for airlines and travel agents says that CBP will return a “System Error” message, rather than a boarding-pass permission message,  in response to any APIS message with a gender marker other than “F” or M”.

Crucially, CBP didn’t change the APIS regulations when the US Department of State and foreign governments began issuing passports with “X” gender markers. Nor did Congress authorize the issuance of “X” passports. It was done by executive fiat. CRSs, airlines, and travel agencies all modified their databases and interfaces to accept “X” gender markers, and CBP accepted them, in flagrant violation of the APIS rules requiring “F” or “M”.

The US State Department began issuing “X” passports in April 2022. In February 2023, CBP proposed changes to the APIS regulations to require air travelers to provide, and airlines to collect and transmit to CBP, additional information that many travelers would be unable to provide and that would expose travelers to additional threats. That rulemaking is still open, and could be finalized at any time. But even when it was reviewing and proposing to revise the APIS regulations, CBP didn’t propose any change to the portion of the regulations it was violating that allowed only “M” or “F” gender markers in APIS data.

CBP must have modified its own systems to accept “X” gender markers in APIS transmissions, since travelers with “X” passports were issued boarding passes and allowed to fly.  We also presume that there was some extra-legal CBP guidance about how to code “X” passports in APIS transmissions issued to airlines through Security Directives or other “Sensitive Security Information” channels.

We don’t know why CBP chose to violate its own regulations and forms rather than modify them to recognize the validity of passports with “X” gender markers, as it easily could have done. But this is in character for CBP, which has often ignored the law. There’s no basis in law for CBP to require common carriers to get CBP permission to board each passenger.

In March 2025, the State Department summarily stopped issuing “X” passports and requested approval for new passport application forms with only “F” or “M” options. That change has been challenged in court, and a preliminary injunction has been issued requiring the State Department to issue or renew an “X” passport for any US citizen who certifies that they are part of the class in the lawsuit. The government has appealed that order and has asked the Supreme Court to stay the injunction while the appeal is pending.

So some (not all) US citizens can still get new or renewal “X” passports. And the State Department says that all previously issued “X” US passports remain valid until their original expiration date. But the APIS regulations still require, as they have always required, that air travelers provide, and airlines transmit, only “F” or “M”.

CBP has now announced to airlines (although with no effort to inform the traveling public) that as of October 14, 2025:

APIS will begin returning a resubmit or “X response” which indicates insufficient information requiring resubmission, when values other than “M” or “F” are submitted in the sex field….

If the travel document presented by a traveler for an international flight to or from the United States has a sex indicator other than “M” or “F” or does not otherwise indicate the sex of the traveler, the carrier or the traveler should select either “M” or “F”. Submitting “M” or “F” in the sex field, in place of the value reflected on the travel document, will not subject the carrier to penalty.

This is a curiously worded statement. It says that “carriers” (airlines, etc.) will not be penalized, but it doesn’t say that CBP will give permission to issue boarding passes for travelers whose passports show their gender as “X” but who submit “M” or “F” APIS data.

We should, by law, have more clear information about what is required and the consequences of not specifying “F” or “M” gender in APIS submisisons. The Paperwork Reduction Act (PRA) requires agencies such as CBP to get approval form the White House Office of Management and Budget (OMB) before any information is collected from the public, and provide notice including the OMB control number and whether the information is required. But we’ve been unable to find a PRA notice or the OMB control number for the collection of APIS information (1651-0088) on any airline or travel agency website or at any ticketing or check-in counter. The current OMB approval for collection of APIS data expires on October 31, 2025. A CBP application for extension of OMB approval is pending, but it is described as being for extension of the current information collection without changes, falling to disclose the plan to change the acceptable  choices of gender markers.

For what it’s worth, none of this says anything about how the Secure Flight program operated by the Transportation Security Administration (TSA) for domestic flights within the US will respond to submissions of Secure Flight Passenger Data (SFPD) that include an “X” gender marker, as is still being used on drivers licenses and ID issued by many states.

Where does this leave a US citizen with an “X” gender marker on their passport?

We see three options, none of them free of risk:

1. Apply to have your “X” passport replaced with an “F” or “M” passport. There’s no guarantee how long this will take, and the fee is the same as for any other passport renewal unless you request the change as a correction of a data error (which may or may not be allowed). The risk of delay in processing your renewal is lowest if you pay the rush fee and apply in person at a Passport Agency office. You may have fewer problems if you have lost your passport than if still have it but say you want it replaced to change the gender marker.
2. Choose “F” or “M” when you make reservations and buy tickets. This may require changing your user profile with the airline or travel agency, or creating a new one. There’s no guarantee that CBP or the airline will allow you to check in, or that the TSA will let you through its checkpoint, if you have reservations as “F” or “M” but you present an “X” passport at the airport. It may vary by airline and/or airport. If you try this please let us know with which airline, at which airport, and how it went.
3. Travel overland to Canada or Mexico, and fly from there. This would be costly in time and money, but a relatively low-risk workaround. There are more and cheaper flights to most of the world form Canada than from Mexico.
4. Try to make reservations, buy a ticket, and travel with an “X” gender marker, and sue the airline and/or CBP if you are refused a ticket or boarding pass. We’d love to see someone challenge the entire travel-permission scheme, which we believe has been illegal from the start. But this is not legal advice, we cant represent you, and any lawsuit like this would be risky. That said, we can see several possible causes of action for such a lawsuit. All of these are likely to be what lawyers call “cases of first impression”, not cases the outcome of which can reliably be predicted:
   • Sue the airline for refusal to sell you a ticket or transport you, in violation of its tariff and its duty as a common carrier. We have yet to see an airline tariff that says an “F” or “M” gender marker is required as a condition of carriage. You could sue in the US or in the country where the airline is incorporated. You might (or might not) have better luck suing an airline based in some other country that still issues passports with “X” gender markers to its own citizens.
   • Sue CBP for illegally ordering the airline not to issue a boarding pass. There are several possible grounds for such a lawsuit, from a narrow challenge to the change in CBP practice without following the rulemaking procedures in the Administrative Procedure Act (APA), to a broad challenge to CBP’s claimed authority to condition common-carrier travel on prior CBP permission.
   • Challenge the denial of passage under the Paperwork Reduction Act (PRA). No PRA notice or OMB control number is displayed at any of the places where APIS information is collected from travelers, and the PRA makes this a defense against any sanctions for failing to provide information. But PRA case law is sparse, and trying to fly if you aren’t given permission would be very risky.

Requiring travelers to specify a sex that matches neither their valid government-issued documents nor their gender identity serves no legitimate “ID verification” purpose.

We welcome reports from international travelers to or from the US with “X” passports.