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Reference

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BR-CO-9 VAT identifiers must carry an ISO 3166-1 alpha-2 country prefix

The Seller VAT identifier (BT-31), Seller tax representative VAT identifier (BT-63) and Buyer VAT identifier (BT-48) must each begin with an ISO 3166-1 alpha-2 country code (for example "DE", "FR", "IT"). Exceptions: Greece may use "EL", and "XI" (Northern Ireland) is also accepted.

Problem Description

ERROR

EN 16931 calculation and consistency rule (BR-CO)

Interactive pipeline

Click a stage to see what it checks, or type a rule ID to light up the stage that reports it.

Try:

BR-CO-09 EN 16931 calculation rule

Reported in stage 2: EN 16931 rules.

Level error: the report recommends rejecting the invoice.

Stage 2 · What it checks

  • The core business terms are present (BR-01 to BR-65).
  • Totals add up and related fields agree (BR-CO); codes and decimals are valid (BR-CL, BR-DEC).
  • Each VAT category is consistent: S, Z, E, AE, K, G, O, L, M (BR-S, BR-Z, BR-AE, BR-IC …).

Example codes

Typical fix

Recalculate totals and VAT from the line data, and correct the VAT category in the source data.

A validator checks an e-invoice in stages. First the file must be well-formed XML that matches the UBL or CII schema (XSD). Then the EN 16931 business rules run: BR core rules, BR-CO calculations, BR-CL code lists, BR-DEC decimals and VAT-category rules such as BR-S. Next come the national or network rules that BT-24 selects: BR-DE for XRechnung, PEPPOL-EN16931 for Peppol BIS Billing. The report lists every failed rule: one error means reject, warnings alone still mean accept. BR-CO-09: EN 16931 calculation rule, reported in the stage “EN 16931 rules”. Rule sets: KoSIT validator 1.6.3 with the XRechnung configuration of 31 Aug 2026 (EN 16931 artefacts 1.3.16), Peppol BIS Billing 3.0.21.

Context and Significance

The validator only checks whether the first two characters are a code from its country list (ISO 3166-1 alpha-2 plus EL and XI). It does not check the rest of the number or whether the number is registered; that is what a VIES lookup does. Peppol routing does not use the VAT identifier but the electronic address (BT-34/BT-49). The error usually occurs when the ERP stores the national number without country code, uses "UK" as prefix, or puts a national tax number (for example a German Steuernummer) into the VAT identifier field instead of the Seller tax registration identifier (BT-32).

Solution

Prefix every VAT identifier with the correct two-letter country code, for example "DE123456789" instead of "123456789". Use "EL" for Greek and "GB" or "XI" for UK VAT numbers, never "UK". In UBL the value is cac:PartyTaxScheme/cbc:CompanyID (with cac:TaxScheme/cbc:ID = VAT); in CII it is ram:SpecifiedTaxRegistration/ram:ID with schemeID="VA".

Quick actions

Validate XMLConvert invoice

Valid Examples

  • BT-31 = "DE123456789"
  • BT-48 = "FR12345678901"
  • BT-63 = "IT12345678901"
  • BT-48 = "EL123456789" (Greece)

Invalid Examples

  • BT-31 = "123456789" (no DE prefix)
  • BT-48 = "UK123456789" (UK is not an ISO 3166-1 alpha-2 code; use GB, or XI for Northern Ireland)
  • BT-63 = "EU123456789" (EU is not an ISO 3166-1 alpha-2 country code)

Affected Fields

BT-31 Seller VAT identifier
BT-48 Buyer VAT identifier
BT-63 Seller tax representative VAT identifier

Validation Tools

Official KoSIT Validator

Run the official KoSIT validator with the XRechnung configuration to check EN 16931 and XRechnung rules.

Convert PDF to XRechnung

Find validation errors during conversion and review each correction.