BR-13: Add the total without VAT to the monetary totals

The short answer

BR-13 fails when cac:LegalMonetaryTotal has no cbc:TaxExclusiveAmount child. Add it directly after cbc:LineExtensionAmount, holding the line total minus cbc:AllowanceTotalAmount plus cbc:ChargeTotalAmount, rounded to two decimals.

This is the net figure the VAT is charged on, and two later checks start from it. Expect BR-CO-13 and BR-CO-15 beside this rule until the element is present.

What the rule checks

The rule runs on cac:LegalMonetaryTotal and passes as soon as a cbc:TaxExclusiveAmount child exists. It does not look at the figure; BR-CO-13 checks the value.

A schema-valid document cannot hold an empty amount. When tried, a self-closing cbc:TaxExclusiveAmount carrying only its currencyID failed the XSD layer, so this rule was never reached.

The total is needed even when it repeats another figure, for example when there are no document-level allowances or charges and it equals the line total.

How an integration ends up here

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

• The source system stores only the gross total and the VAT, and the net total is never computed for the export.
• The mapping leaves out totals it considers redundant, such as a net total equal to the line total.
• The net and gross totals come from one field in the source, and only the gross element is written.
• A calculation upstream returned null for the net total and the serialiser dropped the element.

How to fix it

1. Settle the inputs first: the line total, the document allowance total and the document charge total. BR-CO-10, BR-CO-11 and BR-CO-12 check those.
2. Compute line total minus allowance total plus charge total with decimal arithmetic and round to two decimals. Leave out an allowance or charge total that is not sent.
3. Write the result as cbc:TaxExclusiveAmount, with the document currency in currencyID, between cbc:LineExtensionAmount and cbc:TaxInclusiveAmount.
4. Confirm that the total with VAT equals this figure plus the VAT total, which BR-CO-15 checks next.

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: the monetary totals go straight from the line total to the total with VAT

<cac:TaxTotal>
  <cbc:TaxAmount currencyID="GBP">5.00</cbc:TaxAmount>
  <!-- VAT breakdown omitted from this fragment -->
</cac:TaxTotal>
<cac:LegalMonetaryTotal>
  <cbc:LineExtensionAmount currencyID="GBP">25.00</cbc:LineExtensionAmount>
  <cbc:TaxInclusiveAmount currencyID="GBP">30.00</cbc:TaxInclusiveAmount>
  <cbc:AllowanceTotalAmount currencyID="GBP">0.00</cbc:AllowanceTotalAmount>
  <cbc:ChargeTotalAmount currencyID="GBP">0.00</cbc:ChargeTotalAmount>
  <!-- prepaid, rounding and payable amounts omitted from this fragment -->
</cac:LegalMonetaryTotal>

Fragment of the corrected invoice: the total without VAT of 25.00 sits between the two

<cac:LegalMonetaryTotal>
  <cbc:LineExtensionAmount currencyID="GBP">25.00</cbc:LineExtensionAmount>
  <cbc:TaxExclusiveAmount currencyID="GBP">25.00</cbc:TaxExclusiveAmount>
  <cbc:TaxInclusiveAmount currencyID="GBP">30.00</cbc:TaxInclusiveAmount>
  <cbc:AllowanceTotalAmount currencyID="GBP">0.00</cbc:AllowanceTotalAmount>
  <cbc:ChargeTotalAmount currencyID="GBP">0.00</cbc:ChargeTotalAmount>
  <!-- prepaid, rounding and payable amounts omitted from this fragment -->
</cac:LegalMonetaryTotal>

The corrected invoice has a cbc:TaxExclusiveAmount of 25.00 between the line total and the total with VAT; it is absent from the failing one, which is otherwise identical. Two EN 16931 rules fail beside BR-13. BR-CO-13, at the monetary totals, expects the total without VAT to equal 25.00 - 0.00 + 0.00 and finds nothing to compare. BR-CO-15, at the document root, needs the total without VAT to confirm that it plus the VAT total of 5.00 gives the total with VAT of 30.00. Adding the element clears all three.

Where it applies

• Applies to UBL Invoice and CreditNote in the same way. When tried, a credit note without the total reported the same three rules, and so did the richer example with document allowances and charges.
• The UBL schema does not require this element, which is why the failing document passes the XSD layer and the gap is only caught by the EN 16931 rules.
• While the total is missing, BR-CO-15 cannot tell you whether the total with VAT is right. Recheck it once the element is back.

Related rules

• BR-CO-13 checks that the total without VAT follows from the line, allowance and charge totals
• BR-CO-15 adds the VAT total to this figure to check the total with VAT
• BR-12 requires the line total that this figure is built from
• BR-DEC-12 limits the total without VAT to two decimals
• 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 2026-09-24.1: source checked 2026-09-24, explanation last updated 2026-09-24.

The official definition of BR-13 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.