BR-Z-03: Add a seller VAT identifier when a document allowance is Zero rated

The short answer

BR-Z-03 fails when an allowance carries a cac:TaxCategory with cbc:ID of Z under the VAT scheme and the document has neither a seller tax identifier, under any scheme, nor a tax representative VAT identifier. Restore the seller's cac:PartyTaxScheme with its VAT number, or add the representative that accounts for the VAT.

In the recorded example the volume discount of 2.50 reduces Zero rated supplies, and the Zero rated line beside it raises BR-Z-02 for the same missing identifier. One seller cac:PartyTaxScheme clears both.

What the rule checks

The rule looks for an allowance, meaning cbc:ChargeIndicator of false, whose cac:TaxCategory has cbc:ID of Z and a tax scheme that reads as VAT once trimmed and upper-cased. When tried, the discount with its scheme written as vat still reported this rule, with BR-Z-02.

On the seller side, a cbc:CompanyID in any seller cac:PartyTaxScheme satisfies it, and so does a cac:TaxRepresentativeParty/cac:PartyTaxScheme/cbc:CompanyID under VAT. When tried, adding a representative with GB987654321 under VAT to the failing invoice made it valid.

A representative under another scheme does not count. With TAX as the representative's scheme, the discount invoice reported this rule, BR-Z-02 and BR-56.

The allowance does not have to sit at document level. When tried, a Zero rated invoice without a seller identifier, whose only Zero rated allowance was inside its line, reported this rule and BR-Z-02, with the warning UBL-CR-558.

How an integration ends up here

Possible causes, from the shape of the rule rather than from measured usage:

• The seller party is written from a record with no VAT number, and on a Zero rated invoice nothing in the totals draws attention to the gap.
• A volume or trade discount is added by a separate pricing step that copies the Zero rated category from the lines, while the seller details come from an incomplete template.
• The tax representative's VAT number is sent under a local scheme name.
• The seller VAT number is placed in cac:PartyLegalEntity/cbc:CompanyID rather than in cac:PartyTaxScheme.

How to fix it

1. Confirm the seller's VAT registration and take the number, with its country prefix, from the seller record.
2. Add a cac:PartyTaxScheme to the seller party with that cbc:CompanyID and a cac:TaxScheme/cbc:ID of VAT, between cac:PostalAddress and cac:PartyLegalEntity.
3. If a representative accounts for the VAT, send cac:TaxRepresentativeParty with its name, postal address and a cac:PartyTaxScheme under the VAT scheme.
4. Validate again: the same change clears BR-Z-02 for the Zero rated lines, and BR-Z-04 if the document also has a Zero rated charge.

Validate your corrected invoice

Before and after

These are fragments, not complete documents. The complete synthetic documents they come from are linked below.

Fragment of the failing invoice: a Zero rated volume discount, and a seller party with no PartyTaxScheme

<cac:AccountingSupplierParty>
  <cac:Party>
    <cbc:EndpointID schemeID="0088">7300010000001</cbc:EndpointID>
    <!-- postal address omitted from this fragment -->
    <cac:PartyLegalEntity>
      <cbc:RegistrationName>Example Supplier Ltd</cbc:RegistrationName>
      <cbc:CompanyID>12345678</cbc:CompanyID>
    </cac:PartyLegalEntity>
  </cac:Party>
</cac:AccountingSupplierParty>

<cac:AllowanceCharge>
  <cbc:ChargeIndicator>false</cbc:ChargeIndicator>
  <cbc:AllowanceChargeReasonCode>95</cbc:AllowanceChargeReasonCode>
  <cbc:AllowanceChargeReason>Volume discount</cbc:AllowanceChargeReason>
  <cbc:Amount currencyID="GBP">2.50</cbc:Amount>
  <cac:TaxCategory>
    <cbc:ID>Z</cbc:ID>
    <cbc:Percent>0</cbc:Percent>
    <cac:TaxScheme>
      <cbc:ID>VAT</cbc:ID>
    </cac:TaxScheme>
  </cac:TaxCategory>
</cac:AllowanceCharge>

Fragment of the corrected invoice: the seller VAT identifier restored in the seller party

<cac:AccountingSupplierParty>
  <cac:Party>
    <cbc:EndpointID schemeID="0088">7300010000001</cbc:EndpointID>
    <!-- postal address omitted from this fragment -->
    <cac:PartyTaxScheme>
      <cbc:CompanyID>GB123456789</cbc:CompanyID>
      <cac:TaxScheme>
        <cbc:ID>VAT</cbc:ID>
      </cac:TaxScheme>
    </cac:PartyTaxScheme>
    <cac:PartyLegalEntity>
      <cbc:RegistrationName>Example Supplier Ltd</cbc:RegistrationName>
      <cbc:CompanyID>12345678</cbc:CompanyID>
    </cac:PartyLegalEntity>
  </cac:Party>
</cac:AccountingSupplierParty>

The corrected invoice has a seller cac:PartyTaxScheme with GB123456789 under the VAT scheme, which the failing invoice lacks; nothing else differs. The failing document also reports BR-Z-02 for its Zero rated line. The discount, the Zero rated breakdown of 22.50 and the totals are the same in both documents.

Where it applies

• Applies to UBL Invoice and CreditNote. The credit note built from the recorded example reported BR-Z-02 and BR-Z-03 when tried.
• Reported by the EN 16931 layer as a fatal finding at the document root.
• Charges are covered by BR-Z-04, and Standard rated allowances by BR-S-03.
• The rate of the allowance is a separate check: a Zero rated allowance must be at 0 under BR-Z-06.

Related rules

• BR-Z-02 reports the same missing identifier for the Zero rated lines
• BR-Z-06 requires the Zero rated allowance itself to be at a rate of 0
• BR-S-03 is the Standard rated counterpart for document-level allowances
• BR-56 requires a tax representative, once sent, to carry a VAT identifier
• Browse every rule in the reference
• Background: Understanding EN 16931 validation errors

Scope and source

Written for Peppol BIS Billing 3.0.21 (May 2026), EN 16931 1.3.16, as applied to UBL 2.1 Invoice and CreditNote documents. Other profiles, syntaxes and releases can define this identifier differently. Guidance version 2026-09-28.1: source checked 2026-09-28, explanation last updated 2026-09-28.

The official definition of BR-Z-03 carries the normative wording and test. This page is our explanation of it, not a copy.

Guidance does not change the engine verdict. Fixing this finding does not mean the document passes every layer, and validation does not certify legal or tax compliance or transmit a document over Peppol.