I booked a fare that was labeled as refundable since my travel plans are not completely set in stone. However, when I read more about it on the Delta website, it say "fees may apply". What does this mean, if the ticket said refundable when I bought it?

Also, if I decide I want to upgrade my seat to something better and pay for that, but then end up refunding the trip later, will my seat upgrade also get refunded, or is that a sunk cost?

Thanks. Could not find the answer on the Delta website.

A fee may apply to process the refund.

What type of seat upgrade fee are you talking about? Some are non-refundable/ non-transferable, others are.

$200 fee applies to cancel a nonrefundable ticket (domestic). No fee for a refundable ticket.

Forget the "fees may apply" language. This is boilerplate generic disclaimer.

Check the specific fare rules for each direction of your ticket. Under "Changes" or "Cancellation" it will either list a fee, or it will say "Cancellations Permitted." By saying that, it means it is refundable. Note that the most restrictive fare rules apply to your entire ticket, which is why you need to check the rules for each fare component/direction of your ticket.

As for seat selection and upgrade fees, these are generally nonrefundable even if you cancel/refund the ticket as a result of a voluntary change. If there is a qualifying involuntary change that would allow for a refund, then your seat selection/upgrade fees, even if initially disclosed as nonrefundable, can be refunded due to the involuntary change.

Yes, there are fares out there that are refundable for a fee, it's more common on international fares, and for business class, the fee may be $200-500.
You have to look at the detailed fare rules, usually it's detailed in the "Penalties" section.
You also may or may not have to cancel the reservation prior to the flight's departure to retain the ticket value. That will also be spelled out in the fare rules.

Incorrect. You're thinking change fees.

Note that if you upgrade the ticket this could end up putting you into a nonrefundable fare class, depending on what fare you upgrade into. It's possible that the cheapest upgraded (nonrefundable) fares are cheaper than your refundable coach ticket.

Fare classes have nothing to do with if the ticket is refundable, changeable, or if a fee applies to do either. The fare rules do.

If you upgrade a refundable fare to a non-refundable one, the whole new amount becomes non-refundable. If you upgrade a non-refundable fare to a refundable one, the original non-refundable amount remains non-refundable.

Just curious - at what point in the booking process does DL show the fare rules for a given itinerary? AA's annoying and only shows it at the very end.

So DL's pretty much the same as AA in that respect.

I've used EF and ITA Matrix to find fare rules, but it shouldn't be that hard to find them. Especially when the airlines' like to cite them when things go wrong.

Not quite - on DL the link is available right after you select your flight(s) and it's much less hidden. In the flight summary at the top of the page, like where it says "Changeable / Non-refundable", you can click that and you'll get a pop-up where you can see the rules. There's also a link in the fine print toward the bottom of that page.

On AA.com, the link is only in the fine print, and only AFTER you've entered the passenger information, selected seats, and are on the page where you enter payment information and select "Purchase."

DL definitely > AA on this!

Thanks. I always hated having to do a pseudo booking on AA just to see what the fare rules are. Why go thru the trouble of generating a PNR on their end just to show something that could easily be shown much earlier in the process?