Payable options are receivable system options should have same tax application options.

Tax for inter-company is to be loaded using Create Taxable Transactions in Spreadsheet.

First enter Payable transaction to calculate tax and then for Receivable Transaction.

You should check if any specific rules defined should cover both Sales_transaction and purchase_transaction business category.

Ensure that both the receiver and provider business units and legal entities are subscribed to the applicable tax regime on the transaction date.