BR-E-06: Set the VAT rate of an exempt document-level allowance to 0

The short answer

BR-E-06 fails when an allowance, an cac:AllowanceCharge with cbc:ChargeIndicator of false, has a cac:TaxCategory with cbc:ID of E and a cbc:Percent other than 0. Set that cbc:Percent to 0, the rate of the exempt supplies the discount reduces.

The 20 in the recorded example is the Standard rate. A discount on exempt supplies shares their category and their zero rate; one that really reduces Standard rated supplies belongs in category S at 20 instead.

What the rule checks

Every allowance tax category with cbc:ID of E under the VAT scheme is checked, and the finding points at that cac:TaxCategory. The rule is not limited to the document root: when tried, an allowance inside an exempt line with its own cac:TaxCategory of E at 20 reported this rule as well, next to the UBL-CR-558 warning.

The allowance rate is read as a decimal and must equal 0, so 0.00 passes, as it did when tried. A missing cbc:Percent fails: removing it from the exempt discount reported this rule and nothing else.

Only the allowance is looked at. The exempt breakdown of 20.00 does not depend on the allowance rate, because BR-E-08 subtracts exempt allowances by category, whatever rate they carry.

How an integration ends up here

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

• Document-level discounts are created with a default tax code at the Standard rate, and only the category is changed to match the exempt lines.
• The discount takes its rate from the first line of the order, which was Standard rated when the discount was set up.
• The allowance rate is filled from the seller's default VAT rate whenever the allowance has a category.
• An empty allowance rate is serialised by dropping cbc:Percent.

How to fix it

1. Confirm that the discount applies to exempt supplies. If it does, set cbc:Percent in its cac:TaxCategory to 0 and keep cbc:ID as E.
2. Leave the exempt breakdown as it is. Its taxable amount already nets the discount off the exempt line: 25.00 - 5.00 = 20.00 in the recorded example.
3. If the discount reduces Standard rated supplies instead, change its category to S at the rate, take it out of the exempt taxable amount and into the Standard rated breakdown, and recalculate that breakdown's tax.
4. Where one discount covers exempt and taxed supplies together, split it into one allowance per category, each with its own category and rate.

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: an exempt discount of 5.00 at a rate of 20

<cac:AllowanceCharge>
  <cbc:ChargeIndicator>false</cbc:ChargeIndicator>
  <cbc:AllowanceChargeReasonCode>95</cbc:AllowanceChargeReasonCode>
  <cbc:AllowanceChargeReason>Discount</cbc:AllowanceChargeReason>
  <cbc:Amount currencyID="GBP">5.00</cbc:Amount>
  <cac:TaxCategory>
    <cbc:ID>E</cbc:ID>
    <cbc:Percent>20</cbc:Percent>
    <cac:TaxScheme>
      <cbc:ID>VAT</cbc:ID>
    </cac:TaxScheme>
  </cac:TaxCategory>
</cac:AllowanceCharge>

Fragment of the corrected invoice: the exempt discount at 0

<cac:AllowanceCharge>
  <cbc:ChargeIndicator>false</cbc:ChargeIndicator>
  <cbc:AllowanceChargeReasonCode>95</cbc:AllowanceChargeReasonCode>
  <cbc:AllowanceChargeReason>Discount</cbc:AllowanceChargeReason>
  <cbc:Amount currencyID="GBP">5.00</cbc:Amount>
  <cac:TaxCategory>
    <cbc:ID>E</cbc:ID>
    <cbc:Percent>0</cbc:Percent>
    <cac:TaxScheme>
      <cbc:ID>VAT</cbc:ID>
    </cac:TaxScheme>
  </cac:TaxCategory>
</cac:AllowanceCharge>

Only the cbc:Percent of the exempt discount differs: 20 in the failing invoice, 0 in the corrected one. The failing document reports only BR-E-06. Its exempt breakdown of 20.00 still equals the exempt line of 25.00 less the discount of 5.00, and it carries no tax, so the rate on the discount affects no other rule.

Where it applies

• Applies to UBL Invoice and CreditNote. An exempt credit note with the discount at 20 reported the same rule when tried.
• Reported by the EN 16931 layer as a fatal finding at each exempt allowance cac:TaxCategory whose rate is not 0.
• Zero rated and reverse-charge allowances have the same requirement under BR-Z-06 and BR-AE-06.
• An exempt allowance also requires a seller tax identifier in the document, under BR-E-03.

Related rules

• BR-E-05 requires the rate of 0 on the exempt lines the discount reduces
• BR-E-07 requires the same rate of 0 on an exempt document-level charge
• BR-E-03 asks for the seller tax identifier once an exempt allowance is present
• BR-E-08 subtracts the exempt allowance from the exempt taxable amount
• 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-E-06 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.