Transaction Business Category

Hi Team, 

Can some can help me to understand from which setup Transaction Business category is defaulted. 

1. We have established the Intercompany customer supplier Association

2. We have created the Suppliers and Customers as Internal. 

3. our Tax rules are based on Transaction Business category (.ie Transaction Business category is 'Inter company Transactions' then 0% Tax). 

While creating the Invoices 

1. AR invoice working fine i.e after selecting customer and all required fields while saving the AR Transaction Transaction Business Category is auto populating as 'Intercompany Transactions'

2. For AP invoices Transaction Business category is auto populating as Purchase Transactions our expectation is to populate Intercompany Transactions