For FedEx, to determine who is responsible for paying Shipping Charges and Duty Charges, Shiptheory will process the following in order whichever match first :
- Check if the recipient account number is included in delivery instruction as document here
- Check if the shipment has billing details included already. It can be populated from Shipment API booking, or download from the channel like NetSuite
- Check the preferences set in the carrier's setting
To create a shipment with Restful API, please refer to the document here: https://shiptheory.com/developer/index.html#book
FedEx Shipping Charges and Duty Charges setting:

If you encounter any issues, please feel free to contact our support team. You can call us on 0117 403 4313 (UK) / +1 (629) 666-6726 (US) or reach us online here.