Does my BahnCard discount apply when I book the first class upgrade?

If you have a first class BahnCard 25/50, you will receive the usual 25% or 50% discount when booking the first class upgrade. A second class BahnCard does not grant a discount when booking the first class upgrade. But you must still indicate your BahnCard in your travel profile when booking the upgrade if you also used it to book the ticket. This ensures that the correct price is calculated.