Thanks to the new flexible change fee policy, triggering the Delta credit has never been easier. If you make any changes to your existing airfare like upgrades or flight changes the additional charge will code as u0022Additional Collectionu0022 and trigger reimbursement. If you're purchasing new airfare you should u003cstrongu003epay part of the ticket cost with a Delta gift card and charge the remaining balance to your Amex cardu003c/strongu003e. This will also code as u0022additional collectionu0022 and trigger the Amex airline fee credit. While I have had success on charges over the amount of your credit (i.e. $200 or $250) I always try to keep it right around that number.