PSD2 (Payment Services Directive 2) is an EU directive regulating payment services and payment service providers. PSD2 explained simply: From 14.09.2019, a two-stage verification will help customers to pay securely on the internet. In future, a single password will no longer be sufficient. In the meantime, you will need two or more authentication factors from different categories when making payments or other "activities with a risk of fraud".
For example, a combination of password and fingerprint is conceivable, or a PIN linked to the smartphone. But PIN and TAN are also a valid combination. Your bank decides on the necessity and type of the second authentication. In connection with payment data and payments in our hvv switch app, it can therefore happen that two steps are necessary in the payment process or in the deposit process of a payment type, in which the bank ensures your identity and authorises the transaction. The verification is integrated in the payment process or in the deposit process of a payment method.