Anyone reading about e-invoicing runs into a string of abbreviations: UBL, CII, Factur-X, ZUGFeRD, XRechnung and Peppol BIS. They are often used interchangeably, but they are not all the same thing. This article explains the differences and which e-invoice format your customer will expect in practice.
First, the distinction: standard, syntax and network
Most of the confusion comes from three layers being mixed up.
- The standard: EN 16931 is the European standard that defines which data an e-invoice contains. Almost every format in Europe is based on it.
- The syntax: the way that data is written in XML. The two common syntaxes are UBL and CII.
- The network: Peppol is not a format but a network that invoices are sent over. The format that goes with it is called Peppol BIS Billing 3.0 and uses UBL.
The formats in brief
UBL is a pure XML invoice, meant for machines. There is no PDF attached.
CII is the second XML syntax under EN 16931. You mostly meet it in combination with Factur-X.
Factur-X is a hybrid invoice: a PDF (PDF/A-3) with CII XML embedded in it. A person opens the PDF, a system reads the XML. Factur-X and the German ZUGFeRD are technically the same standard in the latest version, according to the Factur-X maintainers themselves.
Peppol BIS Billing 3.0 is the UBL profile sent over the Peppol network. In Belgium this is the route B2B invoices have had to take since 1 January 2026.
Which format belongs to which country?
- Belgium: Peppol BIS (UBL, compliant with EN 16931). See our article on e-invoicing in Belgium.
- France: UBL, CII and Factur-X are permitted, sent through an approved platform. Read what the French rules do and do not ask of you.
- Germany: in practice XRechnung (pure XML) or ZUGFeRD (PDF with XML). More in our article on Germany.
- Netherlands: B2B e-invoicing is not yet mandatory. See e-invoicing in the Netherlands.
What this means for your invoicing process
You do not need to build every format yourself, but you do need to know what your system can do. Ask yourself three questions:
- Which formats do your customers expect, per country?
- Can your invoicing system produce a structured invoice, and not only a PDF?
- Is the data the format requires, such as VAT numbers and a Peppol ID, correct in your customer records?
That last point is more often the bottleneck than the format itself. You can look up a Peppol ID from within Salesforce, as described in our article on looking up Peppol IDs. A structured invoice is also never better than the source it comes from. Our Billing Platform creates invoices directly from Salesforce, so invoice lines match the order and the data for a format is already in one system.
Not sure which format your customers will ask for, and whether your current invoicing can handle it? Get in touch and we will look at your situation together.