How To Fix 8A121 - The base of withholding tax type & is not defined as modified net amount

8A121 - Overview

• Message type: E = Error

• Message class: 8A - Messages for Argentina

• Message number: 121

• Message text: The base of withholding tax type & is not defined as modified net amount

What causes this issue?

You tried to define for a withholding tax type which tax processing
keys are taken into account to determine the modified net amount. But
the corresponding withholding type is not defined as having the
modified net amount as base.

System Response

The entry is not created.

How to fix this error?

If you want to have the modified net amount as base you have to change
the withholding type definition.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message 8A121 - The base of withholding tax type & is not defined as modified net amount ?

  The SAP error message 8A121 indicates that the withholding tax type specified is not defined as a modified net amount in the system. This error typically arises when there is an attempt to process a transaction involving withholding tax, but the configuration for that specific withholding tax type does not allow for the modified net amount calculation.
  
  Cause:
  
  Configuration Issue: The withholding tax type is not set up correctly in the system. Specifically, it is not defined as a modified net amount in the withholding tax configuration.
  Incorrect Tax Type: The tax type being used in the transaction may not be appropriate for the type of calculation being attempted.
  Missing Master Data: The vendor or customer master data may not have the necessary withholding tax information configured.
  
  
  Solution:
  To resolve this error, you can take the following steps:
  
  
  Check Withholding Tax Configuration:
  
  Go to the SAP Customizing Implementation Guide (SPRO).
  Navigate to Financial Accounting (New) > Accounts Payable >