Preassignment of tax categories in customer output tax is not working in migration cockpit

[SAPSupport]

When a customer BP is created and extended to a sales org, output tax table entries are added automatically. Once the tax categories are determined automatically, user has to just enter value for tax classification. 

While extending a customer through migration cockpit, this functionality is not working. 

How can user update this without having to manually add each tax category as there will be thousands of entries with bulk uploads?

------------------------------------------------------------------------------------------------------------------------------------------------
Learn more about the SAP Support user and program here.

[SAPSupport · Accepted solution]

The automatic derivation of Output tax only works via transaction BP. (Maybe also Fiori and MDG).

In migrate your data and API (technically the same) it is required to provide KNVI data explicitly. The reason is: Only the keys are determined automatically, not the values (typically 0 for not tax-relevant and 1 for tax-relevant, but it varies). But the values might be set to mandatory and then not filled, so throw an error. Even when not mandatory: the empty lines have no meaning, so there is no point of adding them automatically - except in transaction BP (or other UIs) where it enables the user to enter the values for the relevant keys. 

In conclusion, only BP will works. API or migrate your data tool will not automatically extend the output tax.