Four terms that are often confused but each have their own meaning, clearly explained.
E-invoicing comes with many abbreviations. This article explains the four most important terms and how they relate to each other, from the basic technology to the Dutch standard.
XML (Extensible Markup Language) is a markup technology that stores data in a structured text file. An XML file is readable by both computers and humans. Not every XML file is an e-invoice; XML is used for many different purposes. It is the foundation on which the other standards are built.
UBL (Universal Business Language) is an international standard that defines which elements a business document must contain and in what structure. For invoices, UBL specifies which fields are mandatory (such as supplier, buyer, amount, VAT) and how these should be included in the XML file.
UBL is based on the European standard EN 16931, the semantic model that determines which data an e-invoice must contain at a minimum. UBL is one of the two permitted syntaxes for EN 16931; the other is CII (Cross-Industry Invoice).
Peppol BIS Billing V3 is the European Peppol profile that extends UBL with additional validation rules. Where UBL defines the structure, BIS Billing V3 adds checks that invoices must pass:
Every invoice that complies with Peppol BIS Billing V3 is automatically EN 16931-compliant. The standard is regularly updated; the current version (3.0.20) has been mandatory since 23 February 2026.
NLCIUS (Netherlands Core Invoice Usage Specification) is the Dutch implementation of Peppol BIS Billing V3. It adds additional rules specific to the Netherlands:
NLCIUS is mandatory for invoicing Dutch government entities. For B2B invoices within the Netherlands, it is the recommended standard.
The standards build on each other, like layers:
EN 16931 (European standard, semantic model)
└── Peppol BIS Billing V3 (European Peppol profile)
└── NLCIUS (Dutch implementation)
And underneath sits UBL as the syntax binding, the concrete XML structure in which the invoice data is expressed.
Want to see the full picture with all layers and country-specific variants? Then read From semantics to syntax.
Each country can create its own implementation of the European standard, just like the Netherlands with NLCIUS:
eConnect supports all of these standards. Through XML Transformation, the platform automatically converts between the different formats, so you do not need to worry about which standard the receiver expects.
In practice, as an eConnect user you do not need to think about these standards. The platform ensures that every invoice you send complies with the correct standard for the receiver, and that every invoice you receive is processed correctly, regardless of the original format.
If you create invoices manually in the platform, a valid NLCIUS/BIS Billing V3 invoice is generated automatically. If you submit invoices as XML, they are validated and transformed where necessary.
No. The eConnect platform automatically determines the correct format based on the receiver. When sending, a valid NLCIUS or BIS Billing V3 invoice is generated, and when receiving, any supported format is automatically processed. You do not need to make a choice yourself.
For invoices to Dutch government bodies, NLCIUS is mandatory. For B2B invoices within the Netherlands, it is the recommended standard, but Peppol BIS Billing V3 is also accepted. In practice, eConnect generates NLCIUS-compliant invoices by default for Dutch receivers.
Yes. eConnect supports all common European standards, including XRechnung, Factur-X and Svefaktura. Through XML Transformation, the platform automatically converts between formats, so the invoice always arrives in the format the receiver expects.
Want to check whether your XML file complies with the standard? Use the free eConnect Validator.
XML is the base format, UBL is the language built on XML, BIS Billing V3 is the European Peppol profile, and NLCIUS is the Dutch variant with specific requirements for Chamber of Commerce number and VAT. Each layer adds rules to the previous one. eConnect processes and transforms all of these formats automatically.
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