Budget Allocation Prerequisites 
The following settings determine whether a budget can be allocated to a WBS element:
You store a budget profile in the project definition. This profile contains the control parameters for budgeting. In Customizing specify the following under Project System -> Costs -> Budget ->
Specify Default Budget Profile For Project Definitions:The following are ways in which you can assign a budget profile to a project:
Maintain Budget Profile as a default valueIn the profile data of a project definition in Customizing, under Project System -> Structures -> Operative Structures -> Work Breakdown Structure ->
Create Project Profile.
You can allocate budget after the status Created has been reached. If you want to prohibit budget allocation in the Created status, you need to define a user status.
For more information on status management in the project system, and how to create a user status, see
Status Management