CBP Enforces Binary Sex Codes and Strengthens APIS Passport Validation

(U.S. Customs and Border Protection) U.S. Customs and Border Protection is rolling out two APIS data enforcement measures that will change how airlines collect and transmit passenger information for flights touching the United States 🇺🇸. Beginning October 14, 2025, carriers must send only binary sex codes — “M” or “F” in the APIS sex field for every traveler. A separate rule, already in force since October 6, 2025, tightens U.S. passport validation in APIS by rejecting passport numbers that do not match specific formats.

CBP says both steps align federal systems with Executive Order 14168—issued in January 2025 under President Trump—which directs federal agencies to apply binary sex classifications and strengthen document integrity across government platforms.

What CBP will do and immediate effects

• Airlines that submit APIS data with any sex value other than “M” or “F”, including “X” or a blank field, will receive an “X Response — Insufficient Information” from CBP. The carrier must correct and resubmit before wheels-up.
• CBP has begun stricter U.S. passport validation. For U.S. passports, APIS will accept only two formats:
  • Numeric format: nine digits, starting with 4 or higher (example: 412345678).
  • Alpha-numeric format: nine characters, first character A, X, Y, or Z, followed by eight digits (example: A12345678).
• Submissions outside those formats generate an “X Response” and must be retransmitted with a compliant number.

According to analysis by VisaVerge.com, these back-to-back changes put operational pressure on airlines and raise practical questions for travelers whose documents or personal identity details don’t fit the new schema.

CBP frames the changes as security and consistency measures to reduce data errors that complicate pre-departure screening at scale.

The agency’s updated guidance (issued July 7, 2025) instructs carriers to apply binary sex coding to all passengers and crew and to ensure U.S. passport numbers match the new validation checks before transmission. While CBP enforces the data carriers send through APIS, travelers will often feel the downstream effects: added questions at the gate and extra time with CBP officers when records don’t line up.

Policy changes overview

Binary sex code requirement

• Effective October 14, 2025, every APIS submission must include either “M” (Male) or “F” (Female) in the sex field.
• CBP’s system will reject any other entry, including the “X” marker used on some U.S. passports and state IDs, or a blank field.
• Carriers must resubmit with “M” or “F” to clear APIS checks.
• Legal basis: Executive Order 14168, “Defending Women from Gender Ideology Extremism and Restoring Biological Truth to the Federal Government,” directing binary sex categories across federal systems.

U.S. passport validation

• Effective October 6, 2025, U.S. passport numbers must match one of two formats:
  1. Numeric: 9 digits, first digit 4–9 (e.g., 412345678).
  2. Alpha-numeric: 9 characters, first character A, X, Y, or Z, then 8 digits (e.g., A12345678).
• Any passport number outside these formats will be flagged and returned with an “X Response”, forcing a corrected resubmission.
• Purpose: reduce invalid entries, false matches, and improve pre-arrival vetting quality.

Carriers must ensure both the sex field and the U.S. passport number are correct before departure. These targeted validations raise the bar on what airlines must verify upstream and how they handle records that don’t fit APIS’s rules.

Operational effects and human impact

For carriers and operations

• Immediate tasks are technical and procedural:
  • Update DCS and PNR interfaces to force “M” or “F” selections.
  • Build U.S. passport validation logic to catch non-compliant numbers at data entry.
• Risks for delayed adaptation:
  • Spike in “X Response” returns.
  • Manifest rework at the gate and potential departure delays.
• Training needs:
  • Teach agents how to handle passports with “X” markers or older-format passport numbers.
  • Define clear internal rules for assigning “M” or “F” when documents lack a binary field.

For travelers

• Travelers with non-binary or unspecified sex markers will see “M” or “F” assigned by the carrier for APIS purposes. This may conflict with personal identity.
• CBP states that a data mismatch alone should not be treated as deception if identity and travel purpose are confirmed, but it can trigger additional screening (primary or secondary inspection).
• U.S. citizens with older-format passports may experience delays if their passport numbers fail validation; carriers may need to consult CBP or request renewal.

Customer service and privacy considerations

• Assignment of “M” or “F” when a document shows “X” requires staff to make a sensitive choice.
• Recommended airline practices:
  • Limit the number of employees who can change the sex field.
  • Log each change and retain an audit trail.
  • Use a standard script to explain that APIS accepts only binary sex codes.
  • Communicate respectfully to reduce confusion and stress.

Industry tooling

• Tools like PnrGo now surface warnings when a passenger record includes unsupported gender markers. These warnings help airlines fix data before submission, but CBP will still reject records containing non-binary values.

Stakeholder reactions

• Advocacy groups call the binary requirement exclusionary, noting many countries and U.S. states recognize non-binary markers.
• Airlines worry about increased call times, longer check-in lines, and customer complaints.
• CBP and government officials emphasize fraud prevention and uniform data.
• Legal observers note potential friction with anti-discrimination laws in some jurisdictions.

Implementation timeline and compliance steps

Timeline (testing and enforcement)

• Sex field (binary code):
  • EDU testing opened September 17, 2025.
  • Production enforcement begins October 14, 2025.
• U.S. passport validation:
  • Testing began September 24, 2025.
  • Production enforcement began October 6, 2025.
• As of October 12, 2025, airlines are finalizing prep for the October 14 binary-sex go-live and are already subject to the October 6 passport validation enforcement.

Recommended carrier checklist (step-by-step)

1. Build and test a binary-only sex field across all APIS-related workflows (DCS, PNR, online/mobile check-in).
2. Add U.S. passport validation at data entry to enforce the two accepted formats; present clear on-screen messages if a number fails.
3. Update training for airport and contact-center staff to handle “X” marker documents respectfully and assign “M” or “F” consistently.
4. Configure warnings for unsupported gender markers (e.g., via tools like PnrGo) and prevent transmission where a CBP reject is likely.
5. Establish escalation paths to airline government affairs or the CBP Carrier Liaison Program for passport numbers that appear valid but fail format checks.
6. Monitor reject rates daily during the first 60 days after enforcement and adjust processes quickly if patterns emerge.

Traveler checklist (quick tips)

• If your U.S. passport number isn’t nine characters, or if an alphanumeric number doesn’t start with A, X, Y, or Z, contact your airline early.
• If your passport or ID shows “X” in the sex field, expect the airline to assign “M” or “F” for APIS and consider arriving early.
• Build extra time into connections, especially with preclearance or tight transfers after U.S. arrival.

Practical notes for minimizing friction

• Most rejects come from legacy records (stored profiles with “X” markers or old passport numbers). Force profile updates at check-in or when customers edit accounts.
• Carriers can reduce manifest friction by running pre-checks that:
  • Block non-binary entries in the sex field before submission.
  • Validate U.S. passport numbers against the two acceptable formats.
• Align Online Travel Agencies and code-share partners on the data rules so binary codes pass through to the operating carrier.

Broader context and closing points

• APIS is the pre-departure pipeline that drives risk assessments and resource planning at U.S. ports of entry. The move to binary sex codes and tighter passport validation reflects a push for standardization—even as it raises questions about how technical rules affect people whose identities or documents don’t fit neatly.
• Parallel systems (Department of State records, verification services) form the backstop for these validations. Carriers are expected to align inputs with the formats those systems accept to reduce manual intervention.
• The immediate reality for carriers is clear and uncompromising:
  • For the sex field, only “M” or “F” passes APIS.
  • For U.S. passport validation, only the two accepted formats will clear the system.
  • Everything else generates an “X Response” until corrected.

CBP encourages carriers to use the agency’s official channels for questions and updates, including the travel industry portal for APIS. For official reference on the APIS program and requirements, carriers and industry partners can review CBP’s APIS guidance at the agency’s site: CBP Advance Passenger Information System (APIS).

The timeline is tight, but testing windows were available before enforcement. Airlines must harden input validation, train staff, and communicate clearly with customers. The October 14 enforcement will test software, script quality, and the system’s ability to insist on data precision—even when people’s lives don’t fit cleanly into a data field.