I had a look at the declaration I made last year, and also the advice I got from the fisc when I specifically asked about the cashback from Wise. This is what it boiled down to, but I don't understand the logic of the calculations - so if anyone can point out errors, or give a clearer explanation I'd be glad:
Suppose, for the sake of argument, the gross cashback paid by Wise (from all accounts) is 100€. They withhold 30€ and pay it to the Belgian tax office, so I get 70€ paid net into my account(s). The declaration would look like this (as of 2024; I haven't yet looked at the forms for 2025):
Box 238 is added to any other interests in box 251; it shows that the gross cashback (100€) has been reduced by approximately 17.6% (within rounding error) to 82€. Then on form 2042, the box 251 is entered in box 2TR (added to any other sums that might belong there) and the crédit d'impôt of 12€ should appear in box 8VL.
There are a couple of things here that puzzle me:
- As Bev says above - why 17.6% ? Seems a bit random.
- Why is it calculated on the net amount? I would have thought the calculation should have been on the gross amount, although as it turns out the result is about the same but it seems a bit of a roundabout way of doing things.
As I said above, my real sums were small and I didn't think it was worth the bother of spending hours and hours to get my head round it all, but being a bit of a perfectionist it's an itch I can't help but scratch.