Irish eInvoicing guide
UBL or CII: choosing an eInvoice syntax
UBL Invoice/CreditNote and UN/CEFACT Cross Industry Invoice are different XML representations that can carry the EN 16931 semantic model. Neither syntax alone determines the transport network or business agreement.
UBL
UBL uses separate Invoice and CreditNote document roots. It is widely used in Peppol BIS Billing and is the syntax supported by this service for optional Peppol document checks.
CII
CII uses the UN/CEFACT CrossIndustryInvoice model. This service accepts the D16B EN 16931 binding and applies the official CII validation artefact.
How to choose
Follow the syntax and profile agreed with customers, networks or procurement platforms. If you control both ends, test code lists, identifiers, rounding and every business scenario—not just whether XML parses.
Authoritative references
- OASIS UBL 2.1 specification — reviewed 2026-08-15
- UN/CEFACT — Cross Industry Invoice standardisation reference — reviewed 2026-08-15
- CEN/TC 434 EN 16931 validation artefacts 1.3.16 — reviewed 2026-08-15
- OpenPeppol — Peppol BIS Billing 3.0.21 — reviewed 2026-08-15