If you are sending IOSS shipments with Royal Mail from Shiptheory, use the following guide to make sure your IOSS numbers are being transferred to Royal Mail 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 Royal Mail, 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 Royal Mail. For more information on which sales channels pass the IOSS number to Shiptheory and how to handle the situation for channels that do not, see our IOSS Setup Guide here.


Step 2: Use the correct Royal Mail services for IOSS


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


  • MTK - International Business NPC Tracked Large Letter
  • MP7 - International Business NPC Tracked Parcel
  • MTO - International Business NPC Signed Large letter
  • MP9 - International Business NPC Signed Parcel
  • MP0 - International Business Parcels Signed Extra Comp Country Priced
  • MTG - International Business NPC Tracked Signed Large Letter
  • MTE - International Business NPC Tracked Signed Parcel
  • MTF - International Business Parcel Tracked Signed Extra Comp Country Pricing
  • DE4 - International Business NPC Untracked Parcel
  • DG4 -International Business NPC Untracked Large Letter
  • DW1 - International Standard Sort 2 Parcel
  • DW1 - International Standard Sort 2 Printed Paper
  • OLA, OTC, OTA & OSA are IOSS ready but currently do not ship to the EU.


Step 3: Check your Royal Mail labels for the IOSS icon


Although the above Royal Mail services support IOSS shipments, the shipment will only be flagged as an IOSS shipment if the shipment is being sent into the EU, regardless of the shipment value, and a valid IOSS number exists on the shipment (see step 1 above).


It is your responsibility to check that your Shipments are being sent as IOSS shipments, which you can do by looking for the black IOSS circle icon on Royal Mail labels. If the below icon is not shown on your label, the shipment will not be considered an IOSS shipment and duty tax is likely to be due, even if the duty tax was paid by your sales channel/marketplace.




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.