Interoperability is defined as:

the ability of a seller or a buyer together acting as trading parties to exchange compliant e-invoices and other supply chain electronic messages containing the essential information elements required by both seller and buyer, irrespective of the information technology environment, back-office systems, or third-party solutions or services used by each.

Where trading parties use different service providers or platforms there needs to be a mechanism to link the parties together through a so-called ‘four corner model’.

EESPA Interoperability Working Group

Since its formation, EESPA has organised its Interoperability Working Group, in which volunteer member representatives actively participate. Its objectives are to:

1. To establish and develop a strategic approach and future direction for EESPA’s interoperability frameworks and activities for approval by the EESPA General Assembly and provide ongoing governance.

2. To make detailed proposals for the development and maintenance of EESPA frameworks, agreements, components and tools, taking account of all relevant business, technical and compliance aspects. These will include the implementation of rules, standards and best practices which will result in practical easy-to-implement interoperability arrangements and create maximum reach and network effects.

3. To fully consult members of EESPA, other stakeholders and interested parties and liaise with other stakeholders with an interest in interoperability frameworks.

4. To provide advice and guidance to EESPA Members on the adoption and implementation of the Multilateral Interoperability Agreement (MIFA) and the bilateral Model Interoperability Agreement (MIA), as well as specific technical, compliance, and operational issues.

Michel Gilis, AdValvas Europe – EESPA IWG Chair

Deliverables: MIA - MIFA - GIF

1. Download the Model Interoperability Agreement (MIA 4.0) and the MIA Companion document v4.0.  

2. Multilateral Interoperability Framework Agreement (MIFA) that is available for implementation within the EESPA community.

3. The GIF document, downloadable at

4. European Multi-Stakeholder Forum on E-Invoicing (EMSFEI): Report on interoperability and transmission of e-invoices with a special focus on the needs of Small and Medium-sized Enterprises (SMEs) – October 2018. Can be downloaded here.

EESPA Interoperability Network (EIN) under development

The EESPA community is committed to providing an eco-system in which trading partners can transact with confidence in the knowledge that invoices and related messages will travel end-to-end reliably and securely, irrespective of whether they are B2B or B2G and seamlessly on a global and local basis.

In 2019, the association resolved to create a new interoperability network for the use of its members based on CEF e-Delivery, as well as employing other components such as an invoice exchange standard and business response messages. The use of an e-Delivery network will provide a much simpler connectivity environment than the current plethora of bilateral connections, which do work, but create unnecessary complexity and cost for members.

EESPA had successfully pursued its objective to create the basis for a fully interoperable eco-system for its members and their customers, chiefly through the mechanisms of Model bilateral (MIA) and multilateral (MIFA) Interoperability Agreements. The MIA has seen considerable adoption and the MIFA is expected to ramp up in the years ahead as the new delivery tools are deployed.

The EIN will have the following business and technical features:

  1. EESPA governed exchange infrastructure using CEF e-Delivery standards based on the AS4 protocol.
  2. A dedicated trust model, allowing for dynamic sender multilateral exchanges.
  3. Publication of participant capabilities using SML/SMP (Service Metadata Locator/Service Metadata Publisher) to allow for dynamic discovery.
  4. The document standard for e-Invoices will be the implementation of the EESPA e-invoice UBL standard as an extension to the EN 16931 core definition.
  5. Response messages will be used in the form of a Message Level Response- MLR and an Invoice Response- IR to indicate current transaction status at the business level.
  6. EESPA Model Interoperability Agreements (MIA and MIFA), will be used to permit control by members over the compliant invoices they are willing to send, receive, and process on behalf of clients.
  7. Following the completion of two pilots there will be a further roll-out phase to create a critical mass of users actively supporting client transactions.
Global Interoperability Framework (GIF)

The Global Interoperability Framework (GIF) has been created by an international group of associations and bodies with a common interest in overcoming barriers to interoperability for the exchange of supply chain digital transactions. They formed a joint working group (GIF Working Group) in 2019 to develop a neutral framework for collaboration, which could have application in many environments across the globe:  

  • Connect ONCE (ONCE), the Open Network for Commerce Exchange (USA), a collaborative forum for B2B e-Commerce;

  • EESPA, the European E-invoicing Service Providers Association (EU), a pan-European trade association, whose members are active in electronic invoicing and supply chain automation;

  • OpenPeppol (EU) a not-for-profit association responsible for the development, maintenance and implementation of the PEPPOL specifications enabling cross-border e-Procurement;

  • The Business Payments Coalition- BPC (USA), a volunteer group of organisations and individuals working together to promote greater adoption of electronic business-to-business invoices, (B2B) payments, and remittance data.

The Global Interoperability Framework (GIF) is a set of recommended practices, policies, and standards for the operation of any ‘four-corner’ interoperability network organised within a collaborative governance framework wishing to be GIF compliant. Such a network allows its dedicated access points, which are typically service and solution platform providers of various kinds, to quickly and easily inter-connect their extensive customer networks for the secure and robust exchange of digital supply chain-related transactions such as e-invoices and orders. The GIF objective is to enable smoother implementation of end-user business connections by building economies of scale and scope using well-accepted technologies and building blocks.

The EESPA Interoperability Network (EIN) described above will be a fully compliant instance of the GIF.


EESPA is a member of the following forums and bodies with an interest in interoperability: 

  • CEN/TC 434 standards committee responsible for EN 16931: liaison partner
  • CEN/TC 440 eProcurement: liaison partner
  • Connecting Europe Facility (CEF): member e-Invoicing Advisory Group
  • OpenPEPPOL Association- reciprocal associate member
  • Business Payments Coalition (BPC) e-invoicing group
  • European Multi-Stakeholder Group on e-Invoicing (EMSFEI)