EN 16931 CII

Writes the European electronic invoice as UN/CEFACT CII, the syntax France and Germany read. Factur-X and XRechnung both sit on it.

Install

dependencies:
  en16931: ^0.1.2
  en16931_cii: ^0.1.2

Write an invoice out

Build it with en16931, check it, then hand it over.

import 'package:en16931/en16931.dart';
import 'package:en16931_cii/en16931_cii.dart';

final invoice = Invoice.fromLines(
  number: '2026-0042',
  issueDate: DateTime(2026, 9, 13),
  dueDate: DateTime(2026, 10, 13),
  seller: const Seller(
    name: 'COMAPPS SRL',
    vatIdentifier: 'BE0123456789',
    electronicAddress: Identifier('0123456749', scheme: Scheme.belgianEnterprise),
    address: Address(city: 'Bruxelles', postalCode: '1000', country: 'BE'),
  ),
  buyer: const Buyer(
    name: 'Client SA',
    electronicAddress: Identifier('0987654394', scheme: Scheme.belgianEnterprise),
    address: Address(city: 'Namur', postalCode: '5000', country: 'BE'),
  ),
  lines: [
    InvoiceLine.of(
      id: '1',
      item: const Item(name: 'Consulting'),
      quantity: 8,
      unitPrice: 150.00,
      vatRate: 21,
      unit: UnitCode.hour,
    ),
  ],
);

if (validate(invoice).isEmpty) {
  final xml = writeCii(invoice);
}

Read one back

A supplier invoice goes the other way. What the document does not carry is left out rather than guessed, so validate tells you what the supplier got wrong instead of the reader hiding it.

final received = readCii(xml);

for (final violation in validate(received)) {
  print(violation); // [BR-16] The invoice has no line (BG-25).
}

readCii throws CiiFormatException on three things only: text that is not XML, a root that is not a CrossIndustryInvoice, and a document with no issue date. Everything else is read as far as it goes.

Worth knowing up front

A credit note keeps the same root here, carrying the credit note type code. The other syntax gives it a root of its own, so code that branches on the root has nothing to branch on.

Dates are written as YYYYMMDD inside a string element with a format attribute, not as the ISO date UBL uses.

The currency is stated once for the document. Only the VAT totals carry it again, which is what lets an invoice state its VAT in a second currency.

What it does not do

It does not decide what an invoice has to contain: that is the model's business, and validate from en16931 says whether it holds up. A country puts its own rules on top of the standard, and those live in a profile package: France and Germany both read CII, so en16931_facturx holds the French levels and the hybrid PDF, and en16931_xrechnung what Germany adds. Delivery is a separate choice: the same document goes over Peppol, through a portal, or inside a PDF.

License

Released under the MIT licence.