Overview

• The SEQ code indicates the sequence number for online or kiosk check-in and determines boarding priority when flights are oversold.
• Airlines use the SEQ number as a tie-breaker for involuntary denied boarding if no volunteers come forward.
• More than six million travelers were involuntarily bumped globally in the past year, highlighting the stakes of early check-in.
• The SSSS code flags passengers for secondary screening by the TSA, triggering extra pat-downs and luggage inspections.
• Travel experts recommend setting reminders to check in 24 to 48 hours before departure and ensuring group members check in together.