IOSS Technical Information

This page includes the technical information for IOSS, as well as the changes for the versions.

The EU VAT Import One-Stop Shop (IOSS) page has information about setting up the system if you are supplying goods to the EU and the IOSS Questions and Answers page has a list of questions raised about IOSS and KC.


The Import One-Stop Shop (IOSS) is the electronic method of submitting your VAT e-commerce obligations on distance sales of ALL goods imported into the EU, and has been live since 1 July 2021, see European Commission - IOSS for more details.

What Khaos Control changes have been made

All Khaos Control customers will need to do their own research into IOSS to ensure that they understand how these changes affect their business. The changes which are being made, will be based on generic requirements, therefore if you have any specific IOSS changes, please let us know as soon as possible.

From Khaos Control version 8.201 onwards, the following changes will be made:

flashing light bulb!
If you have orders which should NOT have an IOSS number applied but you have a system wide IOSS number set, then you can specify a special blank IOSS value against the associated brand and this will override it but with a blank value. This should only be done in consultation with Khaos Control Support and is considered an advanced feature.

  • A new read-only field will be added to the [ Sales Order | Additional ] tab to show the IOSS number that has been applied to the order, based on brand and system values settings.
  • In the Channels 1.0 and Channels 2.0 configuration screens we have added a place to add IOSS numbers for your channels, and also a checkbox to mark the channel as an External Marketplace, this is intended for channels where they have accounted for the VAT they will pay, this allows for alternative Tax handling within Khaos Control for these orders. The system IOSS opt-in option must be enabled for the Channel IOSS number fields to be visible.

flashing light bulb!
Please do your own research on how external marketplace orders need to be processed. Its our understanding that only orders shipped by you will be affected, so for example Amazon FBA orders will not be subject to IOSS based on the information we have, however please confirm the particulars of your business with each Marketplace you deal with.

  • Orders which are raised from a Channel marked as an External Marketplace, will post any VAT accrued on them, to a new system Nominal "External Sales Tax", and the Tax element will not be posted to the Khaos Control Tax Register.

flashing light bulb!
We are anticipating orders from both Amazon and eBay to present with the GROSS totals including for payments, and the VAT will be calculated within this figure, as such we introduced this External Marketplace flag so we could process any VAT coming into the system via this process to be handled separately. It may be required for manual journals to be raised once the situation is clearer, but any order processed from an external channel will not post its vat to the UK Tax register, only the net Sale.

  • [ System Values | Accounts | Brexit ] will be renamed [ System Values | Accounts | Europe ] with new options added to control tax and threshold information. The Brexit test mode will be repurposed as an EU test mode.
  • In [ System Data | Countries ] Force Country VAT will be renamed Enable Country VAT so you can configure rates, but turn them off if you want to.
  • Default tax rates will be supported on a per country basis instead of the system country only. You can add German tax rates, for example, and specify one as the default. You then do not have to link the rate to all your items, as the system will use the newly designated default.
  • We will be reviewing our Courier integrations and documenting which ones are known to support IOSS shipments to the EU.
  • Where possible we will modify our Courier integrations to pass along required information.

Required Khaos Control Version

The EU IOSS 8.201 Khaos Control update is required for anyone who:

  • Has registered for IOSS to ship goods to the EU
  • Processes orders for Shipping to the EU on behalf of a Marketplace like Amazon or eBay where for orders under 150 Euro IOSS numbers are now mandatory.

If you only process domestic UK goods and do not process orders from any external marketplaces which could be shipped to the EU then you are not required to apply this update. If you process digital UK Tax Returns (MTD) then applying this update will be required ahead of your next submission in July as the Fraud header requirements have changed and the required changes are also included in this update.

06/07/2021 - 19:00pm All customers now have access to 8.201.88 and is now available as of 07/07/21. Email notifications will be sent 07/07/21.

Update Notes:

  • 8.201.64 - Initial release.
  • 8.201.67 - Courier DLL error fixed/resolved - "method Shipper EORI not found".
  • 8.201.82 - This update includes a number of unrelated fixes and also added the ability to override the IOSS number for a selection of Sales Orders from the Sales Order list based upon a green selection.
  • **LATEST** 8.201.88 - This update includes a fix to the Stock screen when interacting with or editing UDAs, and the fix for IOSS numbers being stamped on ROW orders.

If you have any problems with the update please contact our support team.

Known Issues and information

[INVESTIGATING] - 20/09/21 We received a report of Ebay orders for IOSS being imported as Gross when Net figures are being provided by Ebay. This when it occurs is causing the order total to be reduced by the country vat percentage applied to those orders and to misreport figures for ebay. We have only received this report from a single customer, however we recommend all customers spot check any IOSS ebay orders and compare the order totals on Khaos Control versus Ebay.

  • [PENDING] Couriers - DPD (Ship @ Ease and DPD API / myDPD) - DPD have announced at the last minute that they will be supported EURO values being passed directly to them instead of values having to be converted to GBP first (which is the current method for DPD). Khaos Control will be adding support for this, however we do not have a timescale for this due to the late notice from DPD about the change.
  • [INFORMATION] 01/07/21 - RM Click and Drop - We have received reports of problems with the Country of Origin within the Item Specific data sent in the Click and Drop CSV files.
01/07/21 - 16:00pm - This was determined to be a red herring and incorrect advice provided by Royal Mail. This has been resolved by the customer affected remapping the file exported to Royal Mail.
  • [INFORMATION] Fedex - Fedex have provided [30/06/2021] additional information which indicates that (v17) is not sufficient to handle some international shipping requirements. We will be reviewing the integration next week.
  • [INFORMATION] Hermes - Hermes are blocking some courier exports to certain countries where an IOSS number is not present despite it not yet being 1st July. This is out of our control, so if this affects your business please contact Hermes for advice on how to proceed.
 01/07/2021 09:30am - Hermes have advised that this error has now been resolved within their API. If you are still experiencing problems please contact Hermes support.
  • [INFORMATION] DPD released an update for their systems on Sunday (27/06/21) evening which has affected some customers regardless of them running 8.201 of Khaos Control, we advise customers to contact DPD directly for help and support with their DPD integration.
  • [INFO] 20/09/21 - Ebay - Ebay have said they would be adding IOSS information into the Address2 field of orders received in some cases, however they have not provided a physical example of how this will appear as such we have not been able to program response or handling of this additional information. 3 months on we are still to see an example where this is the case from ebay. If you do encounter any issues with eBay and IOSS please report it to our support team.
  • [RESOLVED] Royal Mail Click and Drop have introduced a new mandatory requirement with no notice to include the IOSS number within the export file.

This apparently supersedes the previous advice to use the Trading Name facility to map IOSS numbers.

If you have any problems processing orders via Royal Mail please contact Click and Drop support team.
03/08/21 - This has been resolved in version 8.201.121 onwards, and version 8.202.44 onwards.
  • [RESOLVED] Couriers - DPD Ship @ Ease Neo, DPD API - For Business to Business orders additional fields were required for both DPD integrations.
Changes have been made to our DPD integrations to support both the Received EORI and Receiver VAT number being provided for business shipments.
If you are using DPD - please ensure you are running 8.201.93 which includes these additions.
  • [RESOLVED] **ERROR** "ShipperEORI / CompanyName2 method not found". Some users have reported an issue when trying 8.201 on their TEST system, this is currently being investigated as a priority.
29/06/21 - Resolved in 8.201.67 onwards.
  • [RESOLVED] Standard Web Services 1.0 - We did not have an exposed tag for explicitly identifying orders which are from an external marketplace for tax liability purposes.
Note: This has been resolved in 8.201.67 onwards.
  • [RESOLVED] '06/07/2021 - Stock screen - editing information on the Telesales or Upsell Cross sell tabs can cause an "Invalid Pointer" error. This is currently being investigated and a solution will be released as soon as possible.
Unrelated to the EU IOSS functionality but affecting the 8.201 version, we will be remediating this problem as soon as possible and re-releasing updates.
06/07/2021 - 8.201.88 is now available for those affected by this problem, and will be released to all other systems this evening.
  • [RESOLVED] 02/07/2021 - Marketplace orders from Channels 1.0 and Channels 2.0 for ROW having Channel IOSS numbers applied to them.
 05/07/2021 - We have made changes to prevent IOSS numbers applying to non-EU orders imported from Channels. 
 For the time being we recommend using the 8.201.82 facility to Manually reset any USA orders which have had an IOSS number applied to them.
 06/07/2021 - We are re-releasing 8.201.88 to all customers to resolve this issue, all updates will have been sent by 7pm and an email notification will be sent tommorow morning.
 If you need assistance using this facility please contact our support team.
  • [RESOVLED] Martketplace IOSS numbers, we suspect that some marketplaces will not provide IOSS numbers until after orders have already been imported. As such we will be making a modification to allow the Sales Order IOSS number editable.
29/06/2021 16:00 - We have made these changes and they will be included in 8.201.72, 
30/06/2021 19:00 - We have made further alterations based on feedback and experiences today, which include adding a facility to manually update the IOSS number on a selection of orders from the Sales Order list. 
01/07/2021 09:00 - An update for version 8.201.82 has been released including these changes, a notice regarding these changes has now been sent. 

Courier Support

Not all couriers have yet announced how this will work on a technical level. As with Brexit each courier will have a different approach to this and as and when technical information is received from our Courier partners, we will update our integrations where possible. If your courier is not mentioned, please assume it will NOT be supported. So far we have received technical information from the following couriers only:

We have NOT received any information from the following, so at time of writing these courier integrations will NOT have IOSS support: Parcelforce, Amazon Buy Shipping, APC, ParcelHub, Secured Mail, Yodel - Deskdespatch.

We are currently awaiting clarifications from the following couriers, but at present they are not supported:

  • UPS. (we are still waiting for clarification from UPS and have chased them again today).

We have had information from the following couriers that they DO NOT support IOSS order handling. Please contact the courier provider directly:

  • Despatch Bay.

However it may mean that as with Brexit, customers need to review their courier services to ensure they suit their ongoing needs. We believe many of the couriers will add IOSS support through a combination of introducing new Service Codes and combining this with Incoterms stipulations on a service level, some are intending to handle it at the account level, but this is yet to be confirmed.

flashing light bulb!
As soon as the above changes have been completed we will releasing updates to all Khaos Control customers before the July 1st deadline.

Appendix - Web Services (v8.201 onwards)

Note: If you are relaying Orders for an external marketplace via the standard web services, this is not currently supported and the order will not be flagged as external. You can provide an IOSS number, but this will not affect the tax liability behaviour. We are working on additional web service changes to allow to this, in line with the changes we have made to Channels 1.0 and Channels 2.0.

For customers who have integrations using Standard Web Services to provide XML orders which may need an IOSS number, a tag <IOSS_NUMBER> can be added to the <ORDER_HEADER> We have also now added an FROM_EXTERNAL_MARKETPLACE tag (also in ORDER_HEADER). When set to -1 it sets the Sales Order SOFromExternalMarketplace flag, similar to the user controlled check box in Channels 1.0 and Channels 2.0. The external marketplace tag should ONLY be used if the marketplace order has had VAT calculated already and will not be paid by your business, but by the marketplace.

For example:

*** usual tags here ****

When the IOSS_NUMBER is provided in the XML, the import routine will set it against the Sales Order, and will also assign the appropriate EORI Number (either from the SOrder Brand or from System Values) and lock these values against the Sales Order. This means that even when the Sales Order is edited afterwards they won't get updated (as they normally would).

Note: To force a blank IOSS number (i.e. it won't get recalculated by the Sales Order) please pass ##BLANK## in the IOSS tag.

If your website does not have access to a list or appropriate TAX IDs which include any new Country Tax Rates you may have added for Europe, then we recommend against the usage of the TAX_RATE tag as any information provided in this tag will override the Khaos Control Country VAT rate calculations. If your website has a list of your TAX IDs and is providing the correct ones per country, then this is valid. We have seen examples where old UK rates were being transmitted forcing EU orders to use UK tax values.

For web orders where there is EU VAT and this has been charged on the web site and aligns with the Khaos Control configuration we recommend using PRICE_GRS as below:


For scenarios where an order is not subject to EU VAT or it has not been charged and this aligns with your Khaos Control configuration we recommend using PRICE_NET.


Appendix - Web Services - Channels 2.0 3rd Party integrations

If your 3rd Party website needs to specify an IOSS number it can now do so, our github page has been updated to reflect the changes.

Khaos Control Channels 2.0 3rd Party Web Service page

You will also be able to do this on a per channel basis as part of the configuration, but this will assume the same IOSS number for all orders within that channel. You will also be able to mark a channel as an "External Marketplace", this will allow for different Tax liability handling within the system.

See Also

Visit KhaosWikiX at to see the following:

Contact the Khaos Team