fare difference ques.
 

I can make a flight change with NO fees, except I must pay to reflect the difference in fares--what base is DL using? The price for my flight vs. the price for the flight I want to change to on the change dateor the price I paid when I purchased my ticket vs. the price I want to change to on the change date.
If my flight is part of a DL Vacation package how do they know how much I paid?
PS: I want to change from a d1 later to a d1 earlier on the same day.

You'll have to contact DVC not DL to change your flights as not all DL tickets are published fares.

It's of course based on what you paid.

The difference between what you actually paid and today's current price for the flight you want. Historical prices are, well, history.

You could wait for a schedule change and then make the change for free.

Historical prices are history as you note ;)
But important history since what you paid is what defines your starting point as to what you would need to pay in order to change to the current price.

There was a schedule change, I made the flt. change I wanted for free.:D But knowing what the rules are will be useful in the future..
But for DL Vacations, DL does not see what I actually paid [I bought a package], so knowing what I would have paid on the date of purchase would come into play for computing "fare difference".

But for the new flight that you might want to to change to at some time in the future, the thing that matters is the price at that moment in the future, not any historical price

However, if you try to change the return flight after flying the outbound segments, often historical fares are used. This can be much cheaper even though you're making the change closer to your travel date.

In post #3, the poster noted: "It's of course based on what you paid."
I'm confused, especially if I'm flying on a DL Vacation package, where the price I paid is not known to DL [which is why MQDs are Distance based for DL Vacs.]:confused:

I was talking about the new flight that you might change to. Not your existing flight booked with DL Vacations. I I have no clue how DL Vacations works, I have never used them nor do I ever plan to.

The issue is you have a BULK ticket. This is not a ticket you can call DL and make voluntary changes to. They can rebook you if they make a schedule change, but cant do it for voluntary changes. This is why I commented about DLV and BULK fares in my earlier post.

What you're posting about only applies when doing published fares not BULK tickets.

Note DLV can and does also sell published fares. However if you're buying with hotel and the fare is lower than what's available on DL.com, you likely have a BULK fare.

I've booked lots of DL Vacation packages: (1)for many of these the price for the airfare plus the hotel was cheaper than just booking the flights (directly with DL), (2) since these use DISTANCE for computing MQDs, especially with the accelerator, I've flown itns where the MQDs earned were twice what I paid to DL Vacations. (3) for several itns I also got an RDM mileage bonus.