SAP Message 8A122 - The base of withholding tax type & is not defined as modified tax

Diagnosis
You tried to define for a withholding tax type which tax processingkeys are taken into account to determine the modified tax amount. Butthe corresponding withholding type is not defined as having themodified tax amount as base.

System Response
The entry is not created.

Procedure
If you want to have the modified tax amount as base you have to changethe withholding type definition.