The deposit by bank transfer is made to a Belgian IBAN. Do I have to comply with the AWV reporting obligation at the Bundesbank if I make deposits above EUR 12,500?

No, the Belgian IBAN of Aion Bank is only a so-called “omnibus account” that helps to transfer the incoming funds to the respective and independent securities accounts. Since each user receives an individual securities account identifier in the reference field for transferring money, the incoming amount is subsequently transferred to the respective securities account. There is therefore no extra obligation to report to the Bundesbank.