Both travelers must be booked at the same time and on the same reservation, and travel must be reserved and completed by the expiration date on the certificate. If either ticket is canceled, the other will be as well. Finally, the Companion Certificate is only valid on round-trip tickets.

For most major airline credit card programs in 2026, such as those from Delta, Alaska Airlines, and American Express, the companion certificate is strictly for round-trip travel. These certificates are generally not valid for one-way flights or "multi-city" itineraries. If you try to use a Delta Companion Certificate for a one-way trip, the system usually will not allow the booking, or it will "consume" the entire certificate for a flight that is only half the intended value. However, Southwest Airlines' Companion Pass is the notable exception. The Southwest pass is a status benefit rather than a single-use certificate; once you have it, your designated companion can fly with you on any flight you book, whether it is one-way, round-trip, or part of a multi-city journey, provided there is a seat available. For most other carriers, the "round-trip only" rule is a firm requirement designed to ensure the certificate is used for a standard vacation-style itinerary rather than flexible, point-to-point business travel.