Preserve Airline Credits

Don't mean to sound snarky, but the best thing, in my opinion, is to contact the airline directly and plead your case. Especially if you are a part of their loyalty program. We've flown Delta for years and have always found them to be accommodating when possible. There are, of course, times when things can't be changed. But at least you'll be dealing directly with the horse's mouth so to speak. Hope things work out for you.

According to the Google, you can book a new main cabin ticket then cancel (after 24 hours has passed) for a new credit that expires in a year. You'd want to look very carefully at the fare details to make sure you it allows canceling for credit. YMMV, here's an example discussion on the topic: https://www.reddit.com/r/delta/comments/1guxqyn/any_way_to_extend_a_delta_ecredit/

Also, to clarify, you don't have to fly before the March expiration date, you just have to book before then.

It is usually that you just need to book by the time a year is up, not actually travel.

I read this somewhere online and have not tested it; so not sure if it works.

Sometime before it expires book a new main cabin flight with an airfare that is more than the eCredit value with dates that is well after your eCredit expiration date; pay for it with a combination of your eCredit and cash.

Then cancel the new booking sometime after the original eCredit expiration date; supposedly the US airlines will issue you a new eCredit amount to the new airfare with a new expiration date one year from the date you book the new ticket. Note: If you cancel it before the original expiration date; then the airline will simply issue a new eCredit with the original expiration date.

If I were to try this one day; I will probably book a trip itinerary with dates that I would like to take trip. If I do decide to stick to the plan then I don't have to go through the hassle of canceling it. But if I do want to cancel it, I would call the airline ahead of time to confirm if you will get a new eCredit with new expiration date before canceling it; just so you don't end up with an outcome not to your liking.

Thanks everyone. It's what I expected. I just wanted to be sure I wasn't missing something. I appreciate your input.