Default Account Assignment
Default Account Assignment is an assignment of a default Cost Center or Order in the cost element master. This default tells the system to default this Cost Center or Order when you post to this cost element. This default is assigned to Master Data; no configuration is required.
This default is useful when a specific cost element would generally post to the same Cost Center or Order. It saves the user from entering the assignment during data entry.
If the cost element is used during on screen entry of data, the Cost Center or Order will default on the screen. The user is allowed to override that default.
Automatic Account Assignment
Automatic Account Assignment is an assignment of a default Cost Center or Order against cost element + company code combination. This default tells the system to default this Cost Center or Order when you post to this cost element in this company code. This default assignment combination is created in configuration.
This assignment combination is generally created to allow default cost object assignment against cost elements that post automatically i.e. the posting happens in the background. An example is when a Goods Receipt posts against a Purchase Price Difference cost element. The FI document posts in the background and user does not have the option to assign a cost object against this cost element.
I recommend that you should create an entry in this table for every cost element + company code combination that you configure in Materials Management Automatic Postings
[IMG] Materials Management > Valuation and Account Assignment > Account Determination > Account Determination without Wizard > Configure Automatic Postings (Transaction Code OBYC)
If you configure both Automatic Account Assignment and Default Account Assignment against the same cost element, the system will take the Automatic Account Assignment in priority over Default Account Assignment.