If you are sending IOSS shipments with Whistl  from Shiptheory, use the following guide to make sure your IOSS numbers are being transferred to Whistl correctly to avoid double taxation and other import/export issues when shipping into the EU.


Step 1: Setup your IOSS number in Shiptheory


Before any IOSS shipments can be created with Whistl, make sure you have set up either your sales channel or your Shiptheory account so that Shiptheory has the correct IOSS number to send to Whistl. For more information on how to setup IOSS on your account, see our IOSS Setup Guide here.


Step 2: Use the correct Whistl services for IOSS


Not all Whistl services support IOSS shipments. Only the following international services support IOSS. If you do not have access to these services, you may need to speak with your Whistl account manager to have them enabled.


  • International Insight
  • International Standard IOSS


When using the above services the shipment will be flagged as an IOSS shipment as long as you have followed the appropriate steps form the guide in Step 1.


It is your responsibility to check that your Shipments are being sent as IOSS shipments


If you have any questions about IOSS, or if you would like to check your Shiptheory setup, please feel free to reach out to support.