US airlines must use only male or female designations under new federal rule

The CBP explained that after a compliance period, APIS will return a resubmit request if values other than “M” or “F” are submitted in the sex field. As stated by CBP:

"After the compliance period, 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."

This policy applies to international flights entering or leaving the United States; domestic flights are not affected. A U.S. district court in Massachusetts ruled earlier this year that passports containing an X marker remain valid for travel purposes. However, advocacy groups have raised concerns about potential confusion during check-in and immigration processes for non-binary travelers.

Andy Izenson, senior legal director at the Chosen Family Law Center, reported difficulty getting clear guidance from officials at CBP, TSA, and Homeland Security regarding enforcement of this rule.

There is uncertainty over how border agents will handle situations involving travelers with X-marked passports. While efforts continue within the Trump Administration to eliminate X options on all federal documents, a court injunction currently blocks these changes pending further review by higher courts.

Globally, dozens of countries—including Australia since 2003—offer third-sex markers on their citizens’ passports. The International Civil Aviation Organization (ICAO) recognizes X as a valid passport designation.

A study conducted by UCLA School of Law’s Williams Institute in 2021 estimated that more than 1.2 million Americans identify as non-binary; most are under age 29. Official figures do not exist for how many have received U.S. passports with an X marker amid ongoing policy shifts.