EN 16931 explained: the European e-invoice standard

EN 16931 is the European standard for electronic invoicing, published by CEN in 2017 following Directive 2014/55/EU. It does not define a file format. It defines a semantic data model — what an invoice must and may contain — and the business rules that make it consistent.

Business terms and groups

Every piece of information has a number: BT-1 is the invoice number, BT-2 the issue date, BT-31 the seller VAT identifier, BT-112 the total with VAT. Related terms form business groups such as BG-4 Seller or BG-25 Invoice line. Because the numbers are syntax-independent, you can compare a UBL and a CII invoice term by term.

Business rules

• BR-01 … BR-65 — mandatory content, e.g. BR-06 the seller name must be present.
• BR-CO-* — conditions and calculations, e.g. BR-CO-15 total with VAT = total without VAT + VAT.
• BR-S/Z/E/AE/IC/G/O-* — rules per VAT category, e.g. an exempt line needs an exemption reason.
• BR-CL-* — code lists: ISO 4217 currencies, ISO 3166 countries, UNCL5305 VAT categories.
• BR-DEC-* — amounts have at most two decimals.

Two syntaxes

EN 16931-3 binds the semantic model to two XML syntaxes: OASIS UBL 2.1 and UN/CEFACT Cross Industry Invoice (CII) D16B. Both are equally valid. UBL dominates on Peppol; CII is the basis of Factur-X and ZUGFeRD.

CIUS and extensions

A Core Invoice Usage Specification (CIUS) restricts the standard for a community — making optional fields mandatory or limiting code lists. Peppol BIS Billing 3.0, XRechnung, CIUS-RO and the Croatian CIUS are examples. Extensions add fields that are not in the core, such as Factur-X EXTENDED.

VAT categories in one table

• S — standard rate (rate > 0)
• Z — zero rated goods (rate 0)
• E — exempt (rate 0, exemption reason required)
• AE — reverse charge (rate 0, both VAT numbers)
• K — intra-community supply (rate 0, both VAT numbers, delivery data)
• G — export outside the EU (rate 0)
• O — not subject to VAT (no rate, no VAT numbers)
• L / M — Canary Islands IGIC and Ceuta/Melilla IPSI