When generating SEPA payments you might to your surprise have noticed that the processing date is not in the commonly used European format(DD-MM-YYYY). If you the date as DD-MM-YYYY in the payment processing dialog, you get an "Processing date should be in format YYYY-MM-DD" when you generate the SEPA file.
The reason for this behavior is by design. Dynamics AX follows the SEPA schema definition established by the European Payments Council, and here it is specified to use the international date format standard of ISO 8601 standard, which formats the date as YYY-MM-DD