Periodic invoices can be created only for authorized periods for which the processing date has been filled in. You can:

• Raise an invoice at the time of your choice if you select the Invoicing authorization check box and fill in the processing date.
• Pre-enter the processing dates (in the periodic invoicing schedule), and authorize and invoice the periods around the processing date. The Outstanding periods form shows all outstanding periods for the current sales orders. The periods to be processed can be marked using conditional formatting.

Note: Authorized periods can be invoiced only once.