Electronic invoices are far more than digitally sent documents. They are built on structured data, clearly defined standards and technical rules that enable automated processing.
To successfully introduce e-invoicing, a basic understanding of the key formats, standards and data structures is well worth having. In this article, we provide an accessible introduction to XRechnung, ZUGFeRD/XML and Peppol, explain why structured data matters and how systems process electronic invoices.
What actually makes an e-invoice "electronic"?
An e-invoice is not a simple PDF file. Legally compliant electronic invoices are machine-readable and follow defined technical and legal requirements (e.g. DIN EN 16931).
The core characteristics of an e-invoice are:
- Structured data (typically in XML format)
- Standardised data fields
- Clear validation rules
Only with these in place can invoices be read, checked and posted automatically – without any manual intervention.
Why structured data is so important
Structured data forms the foundation for efficient, low-error invoice processing. Unlike unstructured formats such as scanned PDFs, it enables:
- Automatic validation of invoices
- Elimination of manual data entry
- Significantly lower error rates
- Faster approval and payment processes
- Legally compliant archiving
Every piece of information – from the invoice number to the tax amount – sits in a clearly defined data field that systems can reliably interpret.
Structured data is the key difference between a true e-invoice and a document that has simply been sent digitally. Without it, automated processing is not possible.
XRechnung – the XML standard for legal compliance
XRechnung is a purely XML-based invoice format and fully meets the requirements of the European standard EN 16931. It was developed specifically for electronic invoice exchange with public sector buyers, but is gaining ground in B2B environments too.
Typical characteristics:
- Pure XML (no visual PDF)
- Strictly structured layout
- Fully automatable
- High requirements for mandatory fields and validation
Since XRechnung contains no visual representation, it is processed directly by systems in practice.
ZUGFeRD / Factur-X – the hybrid invoice format
ZUGFeRD (known internationally as Factur-X) combines two worlds: a human-readable PDF and embedded XML data for systems. This hybrid format is particularly popular in B2B settings, as it allows both manual review and automated processing.
Advantages of ZUGFeRD:
- Easy to read for users
- Machine-readable for systems
- Compatible with existing PDF workflows
- Multiple profiles available depending on complexity
ZUGFeRD is especially well suited for companies that want to transition to e-invoicing gradually – the PDF is retained as a visual reference, while the embedded XML data already enables automated processing.
XML – the technical backbone of e-invoicing
XML (Extensible Markup Language) forms the technical foundation of almost all e-invoice formats. XML defines data fields, hierarchies and relationships between invoice information.
This makes invoice data:
- Structured and clearly assignable
- Standardised across system boundaries
- Readable and processable regardless of the system used
Systems use XML schemas to validate invoices and ensure that all mandatory information is correctly included.
Peppol – the transmission network
While XRechnung and ZUGFeRD define how an invoice is structured, Peppol defines how it is transmitted. Peppol is a standardised network for the secure exchange of electronic documents between businesses and public sector organisations.
Key characteristics of Peppol:
- Standardised transmission infrastructure
- Unique identification of participants
- Secure and reliable delivery
- International interoperability
Peppol does not replace invoice formats – it transports them. Think of Peppol as the secure infrastructure that ensures your e-invoices reliably reach their destination.
How systems process electronic invoices
Modern e-invoicing systems typically follow a clear sequence:
- Receipt – via email, upload portal or network (e.g. Peppol)
- Validation – checking file structure, XML schema, mandatory fields and calculation logic
- Data extraction – reading the structured invoice data
- Further processing – handover to ERP or accounting systems
- Archiving – audit-proof and legally compliant storage
This automated process saves time, reduces costs and significantly lowers error rates.
Why a basic technical understanding matters
Even for companies relying on software solutions, a basic technical understanding is essential in order to:
- Select the right formats
- Communicate requirements clearly to suppliers
- Avoid invoice rejections
- Comply with legal requirements
- Scale processes over the long term
Those who understand standards and data structures make better decisions and are well prepared for future requirements. Invest in your team's foundational knowledge – it will pay off in the long run.
Conclusion: Technology as the foundation of efficient invoicing
E-invoices are built on clear standards, structured data and reliable technical frameworks. Formats like XRechnung and ZUGFeRD, technologies like XML and networks like Peppol work together to enable fully automated, legally compliant invoice processing.
Companies that understand these technical foundations lay the groundwork for efficient processes, reduced manual effort and sustainable digitalisation in their finance operations.
