CIUS: national variants of EN 16931
A CIUS is a country-specific restriction of EN 16931. It takes the shared core model and tightens it: makes fields mandatory, narrows code lists, adds validation rules. The key word is restriction, a CIUS adds no new fields. That is exactly what sets it apart from an extension.
CIUS = Core Invoice Usage Specification, a restriction of EN 16931 for a country or sector. It makes optional fields mandatory and adds rules, but stays within the core model. An extension goes further and adds new fields. Examples: XRechnung (DE), Peppol BIS, HR-CIUS, RO_CIUS, CIUS-PT, CIUS-IT. Vera resolves the right CIUS per target country.
What a CIUS does
EN 16931 defines a broad core invoice model with many optional fields. So a country can process reliably and automatically, it sets out via a CIUS what is mandatory in its context. Typical moves: an optional field becomes mandatory, a code list is narrowed to allowed values, an extra validation rule is added. A CIUS always stays compatible, any compliant EN 16931 invoice can be checked against it.
CIUS vs extension
| Aspect | CIUS | Extension |
|---|---|---|
| Action | restricts | extends |
| New fields | no | yes |
| Processability | by any EN 16931 recipient | only with knowledge of the extension |
| Example | XRechnung, HR-CIUS | sector-specific extra fields |
In short: a CIUS makes the norm stricter, an extension makes it bigger. For cross-border processing the CIUS is the safe route.
CIUS across the EU
- XRechnung: the German CIUS, with a mandatory Leitweg-ID for B2G and KoSIT rules.
- Peppol BIS Billing: the widely used international CIUS for the Peppol network.
- HR-CIUS: Croatia, with a CPA code per line and an operator OIB.
- RO_CIUS: Romania, with the county code (Județ) as a mandatory field.
- CIUS-PT: Portugal, embedded in the national regime of ATCUD and certified software.
- CIUS-IT: Italy, as the EN 16931 variant FatturaEU alongside the national FatturaPA.
FAQ
What is a CIUS?
A restriction of EN 16931 for a country or sector. It makes fields mandatory, narrows code lists or adds rules, but stays within the core model.
What is the difference between a CIUS and an extension?
A CIUS only restricts and adds no new fields. An extension adds fields not foreseen in the core model.
Which CIUS exist in the EU?
For example XRechnung (DE), Peppol BIS, HR-CIUS (HR), RO_CIUS (RO), CIUS-PT (PT) and CIUS-IT (IT).
Is XRechnung a CIUS?
Yes, the German CIUS of EN 16931, with a mandatory Leitweg-ID for B2G and KoSIT rules.
Does Vera pick the right CIUS automatically?
Yes, Vera resolves the right CIUS per target country and validates before download.
The right CIUS per country
Vera produces the correct country-specific CIUS to EN 16931 in the browser, validated before download.
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