Billing Due List 
The billing due list is a collection of billable transactions and deliveries. When a transaction is saved and at least one item is billing-relevant, data from this transaction is transferred to the billing component, checked, supplemented with master data, and saved in a billing due list item.
When billing takes place, billing documents are created based on billing due list items. For more information, see Billing Execution.
Note
In the case of service transaction items with the billing relevancy Transaction-Related Billing After Completion, you need to trigger the transfer of billing-relevant data to the billing due list. You do this in the CRM WebClient UI, on the Release for Billing page.
Integration
You can use an external interface to import data from a non-SAP system into the billing due list. For more information, see Data Transfer to SAP CRM via External Interface.
Prerequisites
You have made the following settings, which influence the generation of billing due list items. You do this in Customizing for Customer Relationship Management, in the section Billing.
Billing type
Billing item category
Item category determination
You have defined the billing relevance of item categories (for
example service contract item, credit memo item, debit memo item) in the relevant
business transaction categories. You do this in Customizing for Customer Relationship
Management, by choosing 
Transactions
Basic Settings Define Item
Categories 
. For more information on the types
of billing relevance, see Billing
Scenarios.
Activities
Generation of Billing Due List Items
When a business transaction containing billing-relevant items is saved, its data is automatically transferred to billing, and the system determines the billing item category to be used for each item.
If the system cannot determine a billing item category (for example, if item category determination is not completely defined), it issues an error message.
Using the appropriate services, the system completes the details of the billing-relevant transaction items and runs processing checks for the transferred items. Items can be rejected, primarily for the following reasons:
Partner checking (based on the partner determination procedure of the item category) finds that there are missing or incomplete mandatory partners.
Pricing does not have all the data needed to create a pricing document (for example, document currency and reference currency is missing).
The system saves all successfully processed and completed data in billing due list items.
Changes to the Billing Due List
If you make changes to transactions after their data has been transferred to billing, the system automatically transfers these changes to the billing due list. The following changes, among others, have an impact on billing:
Business partner data (updates partner data in billing)
Pricing conditions (results in a new pricing document for the billing due list item)
Billing date (updates the old billing due list item)
Quantity increase
Before billing
The old billing due list item is regenerated.
After billing
A billing due list item with a positive quantity difference is generated in addition to the old billing due list item.
Quantity reduction
Before billing
The old billing due list item is regenerated.
After billing
A billing due list item with a negative quantity difference is regenerated in addition to the old billing due list item. The regenerated billing due list item is initially marked with the billing block “Q”. As soon as this item is released by the employee responsible using transaction BEA_DL_03, a credit memo is created.
Deleting or rejecting transaction items