If they said the €2,438 was the "break funding cost" (or a similar phrase), that is the break fee.
It is difficult for me to accurately estimate break fees from KBC because they seem to be using slightly different reference rates to other lenders.
Given how much you could save even if the break fee increases a bit, I'd say just get on with the switch. But:
- Clarify with the broker if you'll be liable for a fee if you pull out of the switch
- Check the break fee again as the switch gets close to completion to make sure it hasn't increased dramatically
Alternatively, if you are confident that the switch will succeed (see
here for the main reasons it might not) you could ask for an updated break fee this week and then break out of the KBC fixed rate and pay the break fee. And then move onto either their 3.0% variable rate (no risk of a future break fee) or their 2.25% 2-year fixed rate (which could have a possible future break fee). The latter will save you about €2,600 in interest over the next year versus your current rate.
This rate is a proxy for the wholesale rate that is affecting your break fee. (Note to other readers: a different rate applies in your case.) As that rate increases, your break fee decreases, and vice versa. Because the rate has increased in the last week,
ask them for an updated break fee. (Wait until Wednesday of this week before asking, I would say.) If it is suitably low, consider breaking out of your current fixed rate to lock in the low break fee.