Retroactive Billing | SAP SD manual guide

Here is a PDF tutorial about Retroactive billing in SAP SD. New pricing agreements that you make with your customers may affect billing documents that have already been processed and settled. If a new pricing agreement is effective before the pricing date of the billing documents, you can perform retroactive billing to call up a list of these documents and reevaluate them with the new price. You can then create additional billing documents to settle any differences.