According to the ECJ in Luxury Trust Automobil (Case C-247/21), the application of the triangular rule requires that the intermediary purchaser indicates, in his invoice, that the recipient is liable for the VAT. The ECJ hence abandons the chosen path of attaching only formal significance to invoice details. "Failed" triangular transactions cannot be cured retroactively. German tax courts have recently answered this question inconsistently. Unfortunately, it remains open whether the simplification for triangular transactions can be applied retrospectively, but without retroactive effect. The next court proceedings are thus pre-programmed.