3706776 - Error "Tax code most be entered" received during invoice creation via API in S/4HANA Cloud Public Edition

During the process for down payment a final invoice linked to the down payment. The invoice is created via API Journal Entry - Post (Asynchronous) but it is not posted due to error "Tax code must be entered".

SAP S/4HANA Cloud Public Edition

Create down payment request and post the invoice via API.

The error message "Tax code must be entered" is hard coded in the system (technically in Function Module FI_TAX_INDICATOR_CHECK / Program LTAX1U27). 

In order to avoid the error message, leave 'Tax category' field of the reconciliation account for the down payment blank in G/L master > Control Data > Tax Category field. If 'Tax Category' has value, even if the checkbox of 'Posting without tax allowed' is set, error occurs. In order to avoid it, indicate a tax code for non-taxable transactions (i.e. tax code with 0% tax).

If a 'Tax Category' is entered in the reconciliation account a tax code is required. In case of down payment and down payment request the flag posting without tax indicator in the reconciliation account has no impact. This is the standard system behavior.

API Reference | Journal Entry - Post (Asynchronous) | SAP Business Accelerator Hub

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