EN 16931 explained: the European e-invoice standard

Behind Peppol BIS, Factur-X, XRechnung and FatturaPA sits one thing they all share: EN 16931, the European standard for the semantic model of an electronic invoice. Understand it once and every national format makes sense.

What EN 16931 actually defines

It defines the core invoice: the list of information elements an e-invoice must (or may) contain, what each means, and the business rules between them. It is format-neutral — it says what an invoice contains, not how it's written.

Key concepts you'll see referenced:

• BT- (Business Terms) — individual fields, e.g. BT-1 invoice number,

BT-112 tax-inclusive amount.

• BG- (Business Groups) — groups of fields, e.g. BG-23 VAT breakdown.
• BR- (Business Rules) — constraints, e.g. BR-CO-15: the tax-inclusive

amount must equal tax-exclusive + total VAT.

Semantic vs syntax

EN 16931 is the semantics. To put it in a file you need a syntax:

• UBL 2.1 — the XML syntax used by Peppol BIS 3.0.
• UN/CEFACT CII — the alternative XML syntax used by Factur-X and ZUGFeRD.

Both carry the same EN 16931 fields; they just tag them differently. See UBL vs CII vs Factur-X.

CIUS and Extensions

Countries rarely use raw EN 16931. They publish a CIUS (a compliant subset with tighter rules — e.g. Peppol BIS, France's cius:1.0) or an Extension (adds fields EN 16931 doesn't have, e.g. France's extended). A CIUS never contradicts the core, so a tool that understands EN 16931 adapts to each.

Why it matters to you

• It's why one invoice model works across the EU — your software maps your

data to EN 16931 once, then emits the right national flavour.

• Its business rules are what validation checks. A rejected invoice almost

always fails a BR-* rule (totals, VAT category, missing mandatory field).

• Public-sector e-invoicing in the EU has required EN 16931 compliance for years;

the B2B mandates now extend it to private trade.

The fields you can't skip

□ Seller + buyer identity, address, VAT/legal IDs (BG-4 / BG-7)
□ Invoice number + issue date (BT-1 / BT-2)
□ Line items with quantity, price, amount (BG-25)
□ VAT breakdown per category (BG-23)
□ Document totals that reconcile (BG-22)
□ Payment means (BG-16)

Where Eurobillr fits

Eurobillr models every invoice on EN 16931, so the same document can be emitted as Peppol BIS 3.0 (UBL) or a French CIUS/Factur-X, with the VAT breakdown and totals built to satisfy the BR-* rules. It validates before sending, so you catch a rule failure as a clear message — not a cryptic rejection.

Related: Peppol BIS 3.0 explained · Factur-X explained.