EN 16931 explained: the standard for e-invoicing
EN 16931 is the European standard for electronic invoices. It defines which information an e-invoice contains, what that information is called, and in which XML syntaxes it may be transmitted. XRechnung, ZUGFeRD, Factur-X and Peppol BIS Billing 3.0 are all based on this standard, and the German Umsatzsteuergesetz (VAT Act) explicitly refers to it for e-invoices.
This article explains the standard itself. To find out which countries are introducing mandatory e-invoicing and by when, read the article E-invoicing in the EU 2026: ViDA and national mandates.
What is the EN 16931 standard?
EN 16931 was developed by the European Committee for Standardization (CEN) in technical committee CEN/TC 434. It was commissioned under EU Directive 2014/55/EU on electronic invoicing in public procurement. The directive requires public contracting authorities in the EU to accept e-invoices that comply with this standard: since April 2019 at central level and since April 2020 at regional and local level.
From the outset, the standard had one goal: an invoice from one country should be machine-processable in any other member state without individual arrangements. To achieve this, it separates two levels:
- Semantics: which information an invoice contains and what it means
- Syntax: how this information is technically represented in a file
What parts make up EN 16931?
The standard is a family of several documents. Only Part 1 is legally binding as a European Standard; the others are technical specifications (TS) or technical reports (TR):
| Part | Content |
|---|---|
| EN 16931-1 | Semantic data model of the core elements of an e-invoice |
| CEN/TS 16931-2 | List of syntaxes that comply with EN 16931 |
| CEN/TS 16931-3-1 to 3-4 | Methodology and syntax bindings to UBL 2.1, UN/CEFACT CII and UN/EDIFACT |
| CEN/TR 16931-4 | Guidelines on interoperability at transmission level |
| CEN/TR 16931-5 | Guidelines for sector-specific and country-specific extensions |
| CEN/TR 16931-6 | Results of the practical test of the standard |
For invoices to public contracting authorities, the European Commission has specified two syntaxes: UBL 2.1 (Universal Business Language) and UN/CEFACT CII (Cross Industry Invoice). Both are XML formats. This is why XRechnung exists in both variants, ZUGFeRD and Factur-X use CII, and Peppol BIS Billing 3.0 uses UBL.
The semantic data model
The heart of the standard is the data model in Part 1. It describes every item of invoice information as a Business Term (BT) and combines related items into Business Groups (BG). Some examples:
| Identifier | Meaning |
|---|---|
| BT-1 | Invoice number |
| BT-2 | Invoice date |
| BT-3 | Invoice type, for example 380 for invoice |
| BT-10 | Buyer reference; in Germany, the Leitweg-ID for public authorities |
| BT-31 | Seller VAT ID |
| BT-112 | Invoice total amount including VAT |
| BG-25 | Invoice line |
Each item has a defined cardinality: it is mandatory, optional or may occur more than once. On top of that come business rules such as "The sum of the line amounts must equal the net amount". These rules can be checked automatically. This is exactly what happens when software validates an invoice before it is sent. For an overview of the fields using the German example, see the article All fields of the XRechnung.
CIUS and extensions: how national formats are created
The standard covers the information needed in most invoices. For country-specific or sector-specific needs, it provides two mechanisms:
- CIUS (Core Invoice Usage Specification): a specification that restricts or refines the standard, for example by making optional fields mandatory. Every CIUS-compliant invoice also complies with the standard. Examples are XRechnung in Germany and Peppol BIS Billing 3.0.
- Extension: an extension with additional fields that the standard does not include. An invoice with an extension can no longer automatically be processed by every recipient. One example is the ZUGFeRD EXTENDED profile.
For ZUGFeRD and Factur-X, compliance with the standard depends on the profile. The EN 16931, EXTENDED and XRECHNUNG profiles meet the requirements for an e-invoice. The MINIMUM and BASIC WL profiles, on the other hand, do not contain all mandatory information and, in the view of the BMF (Federal Ministry of Finance), do not count as e-invoices. The article ZUGFeRD or XRechnung explains which format suits you.
What role does EN 16931 play in Germany?
Since 1 January 2025, § 14 UStG (German VAT Act) has defined an e-invoice as an invoice in a structured electronic format that complies with EN 16931. Alternatively, invoice issuers and recipients can agree on a different format, provided the information required for VAT purposes can be extracted correctly and completely into a standard-compliant format.
In practice, this means:
- Since 2025, all companies must be able to receive standard-compliant e-invoices.
- From 1 January 2027, companies with prior-year turnover of more than 800,000 euros must send them in B2B transactions, and from 1 January 2028 all companies must do so.
- A PDF invoice is not an e-invoice, even if it is sent electronically.
EN 16931-1:2026: what has changed
The original standard from 2017 was designed primarily for invoices to public authorities. In view of the B2B mandates in many countries and of ViDA, CEN has revised Part 1. According to the European Commission, the new version was published in May 2026, which formally withdraws the 2017 version. Invoices under the old version remain permissible during a transition period.
The revision mainly adds information needed in B2B transactions and for the future digital reporting requirements. From 1 July 2030, cross-border B2B invoices in the EU must be issued as e-invoices in accordance with the European standard. National formats such as XRechnung and ZUGFeRD will be gradually adapted to the new version. Make sure your invoicing software keeps up with these updates.
How faktoora works with EN 16931
faktoora creates e-invoices as XRechnung, ZUGFeRD and Factur-X and checks them against the rules of EN 16931 before sending. For recipients abroad, faktoora converts the invoice into the format they require; find out more on the page E-invoicing in Europe.
Frequently asked questions
What is EN 16931 in simple terms?
EN 16931 is the European standard that defines the content of an e-invoice. It sets out a common data model with mandatory and optional fields and allows transmission in the XML syntaxes UBL and CII.
Is XRechnung the same as EN 16931?
No. XRechnung is a German specification (CIUS) of the standard. Every valid XRechnung complies with the standard, but it has additional mandatory fields, for example the buyer reference.
Is ZUGFeRD EN 16931-compliant?
That depends on the profile. The EN 16931, EXTENDED and XRECHNUNG profiles meet the requirements for an e-invoice; the MINIMUM and BASIC WL profiles do not.
Do I need to change anything now because of EN 16931-1:2026?
Not immediately. The previous version remains permissible during a transition period. What matters is that your software provider implements the adapted formats as soon as XRechnung, ZUGFeRD and Peppol BIS follow suit.
Sources
- European Commission: Obtaining a copy of the European standard on eInvoicing
- § 14 UStG, gesetze-im-internet.de
- European Commission: VAT in the Digital Age (ViDA)