Posting keys are defined at the client level and assigned to the company code while entering particular line items into sap. Like in the case of document type, posting key also manage lots of things in sap for a document. In this article we will look into the importance of posting key for a document entry in sap fico.
Debit or credit posting
Each line item in accounting document requires a debit and credit entry for an equal amount to get posted. Sap can not identify which line items are to be debited and credited. Posting key in sap, will define it for the line items. Different keys are defined based on the type of transaction that can be used in a business. Each and every transaction has its own debit and credit keys defined. When you use one of these keys while entering a business transaction, sap debit and credit the line items automatically.
For example: for a general ledger posting when you use key 40 for debit and 50 for credit, sap will debit those line items with key used as 40 and credit others used with key 50. However before posting, total of debit and credit must tally.
We have also transactions which are triggered automatically within sap instead of you entering it manually. For those transactions, assignment of posting key is very important as system will automatically debit and credit the entries.
Like document types and others, posting key also have field status too and manage certain fields that are required while entering a transaction. Through this field status you can manage certain fields at line item level in addition to the field status group assigned to gl master and transactions specific fields.
Type of account
Posting key determines the account type to be entered. That means it will determine whether account type will be a customer account or vendor account or asset account or general ledger account. If you are using key 40 and 50 with customer account then it will not take it to the system as customer account related to a different type of transaction and has nothing to do with general ledger accounting.
In addition to above functions, posting key in a document also defines whether line items are connected to a payment transaction or not, which will help in creating payment notices and analyzing payment history.
Transaction OB41 is used to define posting keys. Sap has defined some default posting for your use. If you want, you can copy to create your own key and start using it according to your business need.