errorEN 16931

`BR-16`:Invoice line must have an identifier

Each invoice line must have a unique line identifier (ID).

Severity

Fatal

Rule set

EN 16931

Country

All EU

Fix type

BLOCKED

Engine Classification

Financial or legal field · Modification blocked by policy

Reason: Line identifiers must be unique and consistent with your accounting system. Automatic assignment could break document references and audit trails.

What is BR-16?

BR-16 is a fatal validation rule defined in the EN 16931 specification. It validates the ID element under Invoice > InvoiceLine in the UBL invoice XML.

When this rule fires, the invoice is non-compliant and will be rejected by Peppol access points and national validation services. The sending system receives a rejection response and the invoice does not reach the buyer.

Target path: XPath: /Invoice/cac:InvoiceLine/cbc:ID

This error requires manual correction — financial fields are protected by policy.Get API Access

Why This Error Matters

Invoice rejected. Without line items, there is no description of goods/services being invoiced.

BR-16 is a hard failure. Invoices that trigger this rule are rejected at the access point and never reach the recipient. In Peppol networks, this means your sending system receives an MLR (Message Level Response) with a rejection status. The invoice must be corrected and re-sent, adding delay to your payment cycle.

Validator Behavior

·Causes invoice rejection
·Error returned: BR-16
·Specification: EN 16931

How to Fix It

Number lines

Use sequential numbers (1, 2, 3...) or your internal line references

Ensure uniqueness

Each line must have a different ID within the invoice

Keep consistent

Line IDs should match your internal order/invoice line numbers

Before / After

Failing XML

<Invoice>
  <!-- cac:InvoiceLine is missing -->
</Invoice>

Corrected XML

<Invoice>
  <cac:InvoiceLine>valid-value</cac:InvoiceLine>
</Invoice>

Technical Reference

XPathXPath: /Invoice/cac:InvoiceLine/cbc:ID

SpecEN 16931

StrategyBLOCKED: Cannot create invoice line items automatically. Line items contain product/service details, quantities, and prices that only exist in your source system. Re-export with line items included.

Code Example

<cac:InvoiceLine>\n  <cbc:ID>1</cbc:ID>\n  <cbc:InvoicedQuantity unitCode="C62">10</cbc:InvoicedQuantity>\n  <!-- rest of line -->\n</cac:InvoiceLine>

Common Causes

·Header-only invoice exported without line details
·InvoiceLine elements failed to export from source
·Summary invoice created without itemization
·Export template missing InvoiceLine section entirely
·Line items filtered out due to zero-value or invalid data

Seeing this in production? The API handles BR-16 automatically. See the fix response →

Commonly Seen In

All invoicing software

Frequently Asked Questions

Each invoice line must have a unique line identifier (ID).

Add a unique ID to each invoice line. This error involves a protected field — Invoice Navigator flags it in your pipeline so your team can correct it at the source.

Yes, BR-16 is a critical error that will cause invoice rejection. It must be fixed before submission to ensure your invoice is accepted by the recipient's system.

BR-16 involves a financial or legal field that cannot be auto-modified by policy. Invoice Navigator detects and flags this error immediately, but the correction must be made manually in your ERP or invoicing software.

BR-16 is commonly seen in exports from All invoicing software. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.

Detect BR-16 Before Submission

This error involves a financial or legal field that cannot be auto-modified. The compliance engine flags it immediately with a clear diagnosis so your team can fix it at the source.

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BR-16:Invoice line must have an identifier