Manual Cost Planning in the Work Breakdown Structure 
Purpose
If controlling and cost planning are the most important elements of project processing for you, use manual cost planning to enter the costs, acitivities, and business processes you expect to occur as your project is executed. You can use cost planning to compare plan and actual costs and analyze variances.
Implementation Considerations
If you use the bottom-up procedure, you enter the planned values in the lower planning elements, and the system then totals them up. If you use the top-down procedure, the planned values are distributed manually from the higher planning elements to the lower ones.
Integration
You use
budget management to manage the approved cost framework for a project.The graphic below shows how cost planning and budgeting complement each other.

Features
There are various planning methods and functions, designed to cover the various degrees of detail available at the different stages of the project.
Plan Integration
Within the framework of integrated project planning, you can settle plan data or business processes, and pass them on to profit centers and the general ledger.
Plan integration in projects is the same as plan integration in internal orders.
See also
Plan Integration for Internal Orders .
Plan-Integrated Projects
Plan-integrated projects offer integrated planning of cost elements and activity inputs with cost centers and business processes in one plan version. The system updates allocations directly in the cost center or business process.
Non-Plan-Integrated Projects
In projects which are not plan-integrated, you can only plan costs and activities locally. No planning takes place in the performing cost centers or business processes.
Planning in More Than One Plan Version
The information available on a project changes as the planning phase progresses. This sometimes makes cost planning in more than one version a good idea. This also how planning usually proceeds in everyday business. For this reason, you can plan projects in any CO versions you like.
See
Plan Versions.Planning Methods
The WBS includes various planning methods in the WBS element, from which you can choose depending on the state of the project and the degree of detail you need.

You can use these methods alternatively or together.
You decide this on the basis of the information available. For example, you can use a unit costing or cost element planning for particular partial tasks and use cost-element-independent hierarchy planning to estimate the costs for the rest.
Hierarchy planning is the simplest type of cost planning. You enter the planned values hierarchically, and they are displayed in the same way.

You estimate the expected costs for a project or planning element by, for example:
Hierarchy planning in the work breakdown structure is the same as
overall planning in internal orders .As more information becomes available as planning progresses, hierarchy planning can act as a starting point for two alternative methods of detailed project cost planning.
You can plan primary costs, revenues, activity inputs, and statistical key figures on a cost element basis.
Unit Costings
If you have information on sources of supply, quantities, and prices, the unit costing is the most detailed project cost planning method available. You can use it to calculate overall and annual costs.