The credit memo posting key in SAP is 02 for credit memos to customers and 21 for credit memos to vendors. These posting keys control how the system posts a credit memo to the corresponding G/L account, determining whether the amount is posted as a debit or credit and which account type is allowed.
What Is a Posting Key in SAP?
A posting key in SAP is a two-digit code that controls the entry of line items in accounting documents. It defines:
- Whether the line item is a debit or a credit
- Which account types are allowed (customer, vendor, G/L, asset)
- Which fields are mandatory, optional, or suppressed on the entry screen
Posting keys are defined in the FI configuration under Financial Accounting → Financial Accounting Global Settings → Document → Line Item → Define Posting Keys. Each key has a number, a name, and a “Debit/Credit” indicator. For example, posting key 01 is a normal customer invoice (debit), and 02 is a customer credit memo (credit).
Credit Memo Posting Keys: 02 and 21
The two main credit memo posting keys are:
- 02 – Customer credit memo (credit side)
- 21 – Vendor credit memo (credit side)
When you post a credit memo to a customer, you use posting key 02 on the customer line. The offsetting entry (usually a revenue or expense account) is posted with a standard G/L posting key, such as 40 (debit) or 50 (credit). Similarly, for a vendor credit memo, the vendor line uses key 21, and the offsetting G/L line uses the appropriate key.
These keys are used in transactions like FB65 (customer credit memo) and FB60 (vendor invoice) – but note that the credit memo versions are FB65 for customers and FB60 for vendors (the same transaction can be used with the correct posting key). In practice, you often enter credit memos via FB65 (customer) and FB60 (vendor), and the system automatically uses the correct posting key based on the transaction type you select.
How to Choose the Right Posting Key
Choosing the correct posting key is critical because it affects the financial statement and the document flow. Here are the factors to consider:
- Account type: Customers use keys 01 (invoice) and 02 (credit memo); vendors use 31 (invoice) and 21 (credit memo).
- Debit/credit indicator: Ensure the key you choose posts the amount to the correct side. For a credit memo, you want a credit to the customer/vendor account.
- Transaction type: SAP transactions like FB65 automatically default the posting key, but you can override it if necessary (though not recommended).
- Special G/L transactions: Down payments, bills of exchange, and other special transactions have their own posting keys (e.g., 09 for down payment, 19 for down payment request).
If you are unsure, check the configuration table TBSL (Posting Key) in your system. You can also use transaction SE16 to view the table and see the allowed account types and debit/credit indicators.
Common Problems and Misconceptions
A frequent mistake is confusing the posting key with the transaction code. For example, some users think that FB65 is the “credit memo transaction” – but FB65 is actually the customer invoice transaction that can also post credit memos if you select the right document type. The posting key is what actually determines the debit/credit nature.
Another common issue is using posting key 02 for a vendor credit memo. That will cause an error because key 02 is only allowed for customer accounts. Similarly, using key 21 for a customer will fail. Always match the key to the account type.
Also, be aware that the posting key controls field status. For example, key 02 might require a payment term, while key 21 might not. If you see field status errors, it’s often because the posting key is not the one you intended.
How Credit Memos Affect Financial Postings
When you post a customer credit memo with key 02, the system posts a credit to the customer account (reducing the receivable) and a debit to the offsetting account (e.g., sales revenue reversal or a clearing account). The exact G/L account used depends on the account determination in the transaction.
For vendor credit memos (key 21), the system posts a debit to the vendor account (reducing the payable) and a credit to the offsetting account (e.g., inventory or expense).
These postings update the general ledger in real time, and the document number is assigned sequentially. Credit memos are often used for returns, rebates, or corrections.
Template: Posting Key Reference Table
| Posting Key | Account Type | Debit/Credit | Typical Use |
|---|---|---|---|
| 01 | Customer | Debit | Customer invoice |
| 02 | Customer | Credit | Customer credit memo |
| 31 | Vendor | Debit | Vendor invoice |
| 21 | Vendor | Credit | Vendor credit memo |
| 40 | G/L | Debit | General debit posting |
| 50 | G/L | Credit | General credit posting |
Sample (fictional): For a customer return of $100, use key 02 on the customer line (credit $100) and key 40 on the revenue reversal account (debit $100).
Frequently Asked Questions
Can I use posting key 02 for a vendor credit memo?
No. Posting key 02 is only allowed for customer accounts. For vendor credit memos, you must use posting key 21. Using the wrong key will result in an error message because the account type does not match.
What is the difference between posting key 02 and 21?
Posting key 02 is for customer credit memos, while 21 is for vendor credit memos. Both are credit postings, but they are linked to different account types. The system uses these keys to validate the account and to determine which fields are available.
How do I find the posting key in an existing document?
You can display the document using transaction FB03 (Display Document). In the line item list, the posting key is shown in the “PK” column. You can also view the configuration table TBSL to see all posting keys.
Can I change the posting key after posting?
No. Posting keys are part of the document header and line items. Once a document is posted, you cannot change the posting key. You would need to reverse the document and re-enter it with the correct key.
What transaction code do I use for a customer credit memo?
Use transaction FB65 for customer credit memos. For vendor credit memos, use FB60 (but select the credit memo document type). Alternatively, you can use FB50 for direct G/L postings, but that won’t update the customer or vendor subledger.
Best Practices and Alternatives
Always verify the posting key before saving. A common practice is to use the “simulate” function (menu: Document → Simulate) to review the accounting entries before posting. This prevents errors and saves time.
If you need to post a credit memo without affecting the subledger, you can use a G/L account posting with key 50 (credit) and key 40 (debit) – but that will not update the customer or vendor balance. For proper subledger updates, always use the dedicated credit memo keys.
For recurring credit memos, you can use the transaction FBD1 (recurring document) with the appropriate posting key. This is useful for monthly rebates or allowances.
If you are unsure about which posting key to use, consult your FI consultant or check the configuration in your system. The correct key is essential for accurate financial reporting.