Mapping Budget Types/Processes from FB to BCS 
When you migrate budgeting data to BCS, the system automatically uses the Former Budgeting value types and budget types to create a “mapping” to the corresponding BCS value types, budget categories and processes. You can use these mapping, or assignment, tables to check migration results and/or define derivation rules for mapping between the exporting Former Budgeting fields and the importing BCS fields (“budget type”).
You must have budget data from previous years that was created in Former Budgeting, to be migrated to BCS, and you must have activated BCS.
In the Implementation Guide go to
Check the predefined settings delivered by SAP in the IMG activities:
Display Assignment Rules for Budgeting Process
Display Assignment Rules for Value Type
Make note of the assignment rules used, since you may need to work with them when defining further budgeting processes in BCS Customizing.
Create your organization-specific BCS budget types and processes in the Implementation Guide of
The assignment/mapping rules for transferring FB data are clear to you and enable you subsequently to check the results of your migration run, define transparent derivation rules, and create any necessary new budget types to assign to the SAP-delivered budget processes.
Note that you may also need to make settings in the IMG migration activity Define Derivation Strategy for Line Items .