Four-corner model (PEPPOL)

That Four-corner model The (English 4-Corner Model) is the basic architecture of the Peppol network: senders and recipients do not exchange electronic invoices directly, but through one certified access point (Access Point).

Functionality

The model has four roles. Corner 1 is the sender: their ERP system generates the business document, typically in the UBL format. Corner 2 is the sender’s access point. Corner 3 is the recipient’s access point. Corner 4 is the recipient, who takes the invoice into their system and processes it further.

The access points function as certified gateways. They forward documents, verify format and business rules, and secure encryption and authentication. The access points communicate with each other using the AS4 protocol. The access point of the receiver is determined by the access point of the sender via two directory services: the Service Metadata Locator (SML) as the only central component of the network and the decentralized Service Metadata Publisher (SMP) with the technical metadata of the participants. Therefore, recipients must be registered in a SMP. Those who only send need not register.

Benefit

Two- and three-corner models often require their own interfaces and individual technical arrangements. The four-corner model, on the other hand, follows the principle of „connecting once, everyone reaches out.“ A company only needs one connection to an access point to reach every registered participant. If a company changes its access point, its address remains the same within the network. This structure reduces the entry barrier, especially for small and medium-sized companies.

In the SAP Business One context

Peppol is considered an open standard for the transmission of business documents such as orders and invoices. A digital document number series can be linked to a business partner to send electronic documents via Peppol. Setting it up is a further topic for the consultant. The Electronic Document Service (EDS) together with the Peppol Exchange Service is considered the standard configuration for the four-corner model.

Demarcation

The four-corner model regulates the transport, not the billing format: Peppol is a transport network, not a format. For example, Peppol BIS Billing 3.0 determines the content. In countries with ongoing government transaction control, such as Poland, sources extend the model with a fifth corner: the tax authority (see Clearance model (E-Invoice)). See also PEPPOL (SAP Business One), Peppol ID and Peppol access point.

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