But Delta finally announced today that upgrade certificates selected between 3/1/19-12/31/20 will be valid through 12/31/21, even if they already expired! Expired certificates will be reissued by 3/8.
Delta is also making them easier to use. They can now be used on award tickets and cash+miles tickets, plus you can now upgrade more than one companion on a flight.
Delta has also added the ability to check if you can confirm an upgrade at the time of booking when you search for a paid or award ticket if you’re eligible for upgrades:
By clicking on “Delta One suites available with Upgrade Certificate” you will get this popup:
Unfortunately you’ll still have to call Delta to apply the certificate and unlike with American, you still can’t upgrade basic economy fares.
Your move American and United!