Peppol SBDH vs AS4: What’s the Difference in E-Invoicing?

No, SBDH and AS4 aren’t two competing e-invoice formats that your business has to pick between. They’re two different layers of the same Peppol delivery, and every invoice you send uses both of them at once. SBDH (Standard Business Document Header) is the envelope that carries the routing information an invoice needs: sender, receiver, document type and process type. OpenPeppol published the newest version, 2.0.2, on 2 July 2026. AS4 is the secure messaging protocol underneath it. Peppol’s AS4 profile, version 2.0.3, sets out how two Access Points — the certified gateways sitting at network corners C2 and C3 in Peppol’s model — exchange encrypted messages. The confusion right now comes from somewhere else entirely. The European Commission approved a separate eDelivery AS4 2.0 profile on 4 December 2024, and that is not the same document as Peppol’s own AS4 profile.

What’s Inside the SBDH Envelope?

SBDH doesn’t format the invoice content. It says nothing about how many line items sit on the invoice or which VAT rate applies. Per the SBDH specification, it’s an adaptation of the UN/CEFACT standard business document header (a long-established international format for describing what’s inside a business message), built so an Access Point can route a message without ever opening the invoice’s actual content. The envelope records who’s sending, who’s receiving, what kind of document this is (an invoice, a credit note) and which business process it belongs to. Those two values, the document and process identifiers, are exactly what an SMP (Service Metadata Publisher) lookup uses to find the right delivery record for the receiver. Put simply, SBDH is the address and routing labels on an envelope, not the letter inside it.

What Does AS4 Do With That Envelope Between Access Points?

AS4 handles how that “letter” — the SBDH plus the business document — physically travels from one Access Point to another. The Peppol AS4 profile describes it as an asynchronous transfer protocol, meaning the sender doesn’t wait for an immediate reply before moving on, operating between corners C2 and C3 of Peppol’s four-corner model. Every message is signed and encrypted using Peppol’s PKI (Public Key Infrastructure, the certificate system that proves a sending or receiving Access Point is genuinely who it claims to be), and the destination is resolved through a dynamic SMP/SML lookup. Only one communication pattern is allowed on the Peppol network: One-Way/Push, where a message goes in one direction and no reply is expected on the same channel. Traffic between Access Points always runs TLS-encrypted over port 443.

Does One E-Invoice Use Both at Once?

Yes, and there’s no other way to do it. The AS4 profile requires, in plain terms, that the SBDH together with the business document be the first MIME attachment (a packaged file-attachment format) right after the attachment carrying the AS4 headers. So SBDH sits inside every single AS4 message sent through Peppol, no exceptions. The SBDH specification confirms the same thing from the other side: every message exchanged over Peppol AS4 has to use the Business Message Envelope. SBDH says what’s moving. AS4 says how it gets there safely. Two descriptions of the same trip, from opposite ends.

Where SBDH and AS4 Differ, Side by Side

	SBDH	AS4
What it is	envelope (header) for the business document	message transfer protocol
What it carries	sender, receiver, document type, process type	encryption, signature, routing between two Access Points
Who uses it	Access Points, for routing — without opening the content	Access Point software, to deliver the message
Identifier	InstanceIdentifier (global ID of the document)	MessageId (technical ID of the delivery attempt)
Current version (31 August 2026)	v2.0.2, published 2 July 2026	v2.0.3, published 22 April 2024

What’s the Difference Between the InstanceIdentifier, the Invoice Number, and the MessageId?

These three get mixed up constantly, since all three look, on paper, like some kind of “ID.”

The InstanceIdentifier

According to the SBDH specification, DocumentIdentification/InstanceIdentifier is a globally unique reference that identifies the SBDH document itself, generated by the sender’s system the moment it builds the envelope.

The Invoice Number

The invoice number is something else entirely: a field inside the business document itself. Take a UBL invoice, for instance (UBL being Universal Business Language, the standard XML format most Peppol invoices are written in), assigned by your accounting software according to your own numbering logic. Peppol’s standards have no say over that format at all.

The MessageId

The AS4 MessageId is a third, unrelated ID. An AS4 application generates one for every transmission attempt, and it identifies that specific technical delivery attempt, not the document.

Whose Identifiers Sit in the SBDH, and Whose Sit in the AS4 Header?

Here too, there are two separate layers.

Inside the SBDH

The SBDH sender and receiver identifiers refer to the business parties. The receiver identifier has to match a Peppol Participant registered in SML/SMP, and a sender identifier is required even when the sender itself isn’t in the registry.

Inside the AS4 Header

The parties named in the AS4 header, by contrast, are the Access Points, the certified providers, whose certificates get checked against the SMP. Short version: SBDH records which company is sending an invoice to which company; the AS4 header records which Access Point is talking to which Access Point.

Is eDelivery AS4 2.0 the Same Document as Peppol AS4?

This is where today’s version confusion actually comes from.

A Naming Collision, Not a Shared Standard

The European Commission’s eDelivery governance board approved eDelivery AS4 2.0 on 4 December 2024. It’s the next generation of eDelivery profiles, built on new cryptography (elliptic-curve cryptography replacing the earlier RSA-based approach) and better certificate handling. That is not the same document as Peppol’s AS4 profile, version 2.0.3, which OpenPeppol published back on 22 April 2024 and which is built on top of an earlier version of CEF eDelivery AS4, version 1.14, not 2.0. The two numbering schemes, Peppol’s “2.0.3” and the Commission’s “AS4 2.0”, simply happen to collide.

No Backward Compatibility, No Firm Deadline

What matters more is this: eDelivery AS4 2.0 isn’t backward-compatible with AS4 1.x at the profile level, so an Access Point speaking 2.0 can’t talk directly to one still running 1.x. Per the Commission’s own documentation, SBDH support stays tied to AS4 1.x usage patterns, and Peppol’s network currently runs on that 1.x family. OpenPeppol’s specification catalogue lists AS4 profile version 2.0.3 as the only version in force today; no migration to 2.0 appears anywhere in it. If someone tells you there’s a firm deadline for AS4 2.0 on the Peppol network, it’s worth asking exactly which source that claim is coming from.

What Does This Mean for Your ERP Integration?

As a developer building or maintaining an accounting or ERP integration, you don’t need to choose between SBDH and AS4, and you don’t swap one for the other.

What Your Integration Actually Needs to Do

Your job is to make sure your system generates a correct SBDH envelope, with the right Peppol Participant identifier for the receiver, and hands it off to a certified Access Point that takes care of the AS4 mechanics on your behalf. If your Access Point already complies with Peppol’s AS4 profile 2.0.3, the SBDH 2.0.2 update, which mainly added the MLS_TO and MLS_TYPE fields for message-status notifications, doesn’t change anything material in your integration.

Who Needs to Worry About eDelivery AS4 2.0

eDelivery AS4 2.0 is a matter for Access Points and service providers directly, who’ll need to update the cryptographic base of their software. For a business sending e-invoices, it’s a background process worth keeping an eye on right now, not something that requires any change to your integration today.