Overhead Key
Specifies which overhead is applied to a reference object (such as a material), which forms a link between overhead conditions and the following:
A material master record
A cost object node of a cost object hierarchy
A general cost object
A sales order item
You can define special overhead conditions for certain reference objects.
Overhead Key for Materials
In order to link materials to certain overhead conditions, you need to:
Enter an overhead group in the costing view of the material master record
Enter an overhead key in the costing sheet that is linked to this overhead group in Customizing for Product Cost Controlling
Based on the overhead key, the overhead is assigned to a particular material through the overhead group in the costing view of the material master.
The overhead group and overhead key are included in the following:
Material costing in Product Cost Planning
In Cost Object Controlling:
In a preliminary cost estimate for the product cost collector or for the manufacturing order
In period-end closing for the product cost collector or for the manufacturing order
Overhead Key for Cost Object Hierarchies
To link cost object hierarchies to overhead conditions, enter the overhead key in the cost object master record.
The overhead key is included in the cost object node when overhead is applied at period-end closing.
Overhead Key for Sales Order Items
To link sales order items to overhead conditions, enter an overhead key for the sales order item. To do this, go into the sales order and choose 
Extras
Account assignment
.
The overhead key is included in Product Cost by Sales Order:
When the planned costs of sales orders are calculated
When overhead is calculated at period-end closing
Overhead Key for General Cost Objects
The overhead key is included:
When planned costs are calculated for general cost objects
At period-end closing
The standard system has various costing sheets containing an overhead key. You can apply overhead to materials by modifying these costing sheets to suit your needs.
Example
You have defined two overhead groups in order to apply overhead to materials. These two overhead groups are linked to two overhead keys. An overhead rate of 10% is specified for overhead key 01. An overhead rate of 20% is specified for overhead key 02.
Example
You have more than one plant. You want to apply overhead only if the material is assigned to a certain plant and overhead key.
The system checks these dependencies when the overheads are calculated. If the dependencies are met, the system calculates an overhead percentage. You need to define this percentage for each of your dependencies.
Overhead Key for Base Planning Objects
In base object costing, you enter the overhead key in the master data for the base planning object.