In SAP Financial Accounting, when you reverse an already posted document, what type of document number assignment must be used for the reversal document?

Introduction / Context:
Reversing posted documents is a common correction process in SAP Financial Accounting. When a user reverses a document, the system creates a new accounting document that cancels the effect of the original posting. This question focuses on how the document number for the reversal document is assigned, which affects traceability and consistency.

Given Data / Assumptions:

• A financial accounting document has already been posted in SAP.
• The user starts a standard reversal transaction such as FB08.
• The reversal is posted in the same company code using the configured number range for reversal documents.
• We are interested in the rule for number assignment for the reversal document itself.

Concept / Approach:
SAP uses number ranges to assign document numbers automatically. For standard financial documents and their reversals, SAP recommends and implements internal number assignment, where the system picks the next available number from the defined range. External numbers are normally used only in special scenarios and are not used when the system generates a reversal document automatically, because the user should not manually control that number in order to guarantee uniqueness and auditability.

Step-by-Step Solution:

Verification / Alternative check:
If you inspect number range customizing for document types, you will see that reversal postings use the same or a specific number range with internal assignment. When performing reversals in a test system, the user is not prompted to enter a document number, which confirms that the system assigns the number internally and consistently for every reversal document.

Why Other Options Are Wrong:
Option A is incorrect because external numbering is not suitable for automatically created reversal documents. Option C suggests manual number entry without a number range, which would violate fundamental SAP control concepts. Option D claims that either internal or external assignment can be used freely, but in practice the reversal process is tied to internal number ranges. Option E is impossible because every posted accounting document in SAP must carry a document number for auditing and reporting.

Common Pitfalls:
Some learners misinterpret the fact that original documents may occasionally use external numbering and assume that the same applies to reversals. In reality, the reversal is a system generated document and therefore follows the internal number range logic. Confusing document numbers with reference numbers or document headers can also lead to misunderstandings about how the reversal is identified.

Final Answer:
The correct answer is Internal number assignment only, because reversal documents in SAP Financial Accounting are created by the system and therefore must receive an internally assigned document number from the appropriate number range.