You need to change the default freight code that is being used by Magento
- Find what default Shipping SKU/item code that is being sent over from Magento (By default it is "Shipping")
- Log into the Avalara Avatax Admin Console.
- Click on the "Organization" Tab.
- Select the company to which you want to add the item.
- Select the "Items" menu.
- Click on the "New" button.
- Add the Shipping item code
- Add a description
- Assign the Shipping item a new freight tax code.
- Click on the Save button.
Now when the Shipping item code is passed in a transaction to the admin console, the new fright tax code will override the default code found in Magento.
Magento's Default tax code is coded into the system and cannot be change through the UI.