errorbusinessEN 16931

BR-23:Missing unit of measure code

Fix: Invoice Navigator automatically fixes this issue by correcting the `@unitCode` element in your Invoice. Upload your invoice to fix this automatically.

Each Invoice line shall have an Invoiced quantity unit of measure code (BT-130). This identifies the unit of measure for the invoiced quantity using UN/ECE Recommendation 20 codes.

Severity
Fatal
Rule set
EN 16931
Country
All EU
Fix type
AUTO-FIX

Engine Classification

Auto-fix: Default to "C62" (unit/piece) which is the standard catch-all unit code. Can also derive from common text patterns like "hours"→"HUR", "kg"→"KGM".

What is BR-23?

BR-23 is a fatal validation rule defined in the EN 16931 specification. It validates the @unitCode element under InvoicedQuantity in the UBL invoice XML.

When this rule fires, the invoice is rejected by Peppol access points and never reaches the buyer.

Target path: cac:InvoiceLine/cbc:InvoicedQuantity/@unitCode

Why This Error Matters

Invoice rejected. Unit of measure is required for price calculation verification.

BR-23 is a hard failure — the invoice must be corrected and re-sent before it can reach the recipient.

Invoice Navigator can automatically correct this error in your pipeline. The fix is applied with full audit evidence, so your compliance trail remains intact.

Validator Behavior

  • ·Causes invoice rejection
  • ·Error returned: BR-23
  • ·Specification: EN 16931

How to Fix It

1.

Identify the unit

Determine the unit of measure (pieces, hours, kilograms, liters, etc.)

2.

Find the code

Use UN/ECE Rec 20 codes: C62 (piece), HUR (hour), KGM (kilogram), LTR (liter), MTR (meter)

3.

Add unitCode attribute

Add unitCode="C62" (or appropriate code) to the InvoicedQuantity element

Before / After

Failing XML
<cbc:InvoicedQuantity>
  <!-- @unitCode is missing -->
</cbc:InvoicedQuantity>
Corrected XML
<cbc:InvoicedQuantity>
  <@unitCode>valid-value</@unitCode>
</cbc:InvoicedQuantity>

Technical Reference

XPathcac:InvoiceLine/cbc:InvoicedQuantity/@unitCode
SpecEN 16931
Operationset_attribute
StrategyAuto-fix: Default to "C62" (unit/piece) which is the standard catch-all unit code. Can also derive from common text patterns like "hours"→"HUR", "kg"→"KGM".

Code Example

<cbc:DocumentCurrencyCode>USD</cbc:DocumentCurrencyCode>
<cbc:TaxCurrencyCode>EUR</cbc:TaxCurrencyCode>

Common Causes

  • ·Unit code not mapped in export template
  • ·Source uses text descriptions (pieces) not UN/ECE codes (C62)
  • ·Default unit of measure not configured in system
  • ·Service lines missing unitCode attribute
  • ·UnitCode attribute omitted from Quantity element

Seeing this in production? The API handles BR-23 automatically. See the fix response →

Commonly Seen In

Multi-currency invoicing systems

Frequently Asked Questions

If VAT accounting is in a different currency, TaxCurrencyCode must be specified.

Add TaxCurrencyCode if VAT is in different currency. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.

BR-23 is a warning that may not always cause rejection, but it indicates a potential compliance issue that should be addressed to ensure full compatibility.

Many instances of BR-23 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including tax currency code when different from document.

BR-23 is commonly seen in exports from Multi-currency invoicing systems. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.

Related Errors

Related Content

Last updated: 27 February 2026

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