The Companion Certificate is issued to eligible Delta cardholders every card anniversary, so you can use it once a year per card. The benefit does not roll over if unused.

A companion voucher, such as the one offered by the British Airways American Express card, is typically a one-time-use reward. Once you redeem the voucher to book a flight for a companion (or for a 50% Avios discount if traveling solo), that specific voucher is considered used and cannot be reused for future bookings. However, you can earn a new voucher each year by meeting the required spending threshold on your eligible credit card. In 2026, the terms generally allow you to hold and even combine multiple vouchers if you have earned them in consecutive years or across different accounts, but each individual voucher code is retired once the travel is booked. It is also important to note that the "main" cardholder must be one of the passengers on the booking for the voucher to be valid, and the travel must usually be completed before the voucher’s expiration date, which is typically 12 to 24 months from the date of issue.