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BR-21:Missing invoice line identifier

Each Invoice line shall have an Invoice line identifier (BT-126). This is a unique sequential number identifying each line item on the invoice.

We can fix this automatically

AUTO-FIX

Auto-fix: Generate sequential line identifiers (1, 2, 3...) for each invoice line. These are internal reference numbers, not product codes, so sequential generation is safe.

No manual changes needed
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Why This Error Matters

Invoice rejected. Line identifiers are required for referencing specific items in disputes or corrections.

How to Fix It

1

Identify lines without ID

Find all cac:InvoiceLine elements that are missing the cbc:ID child element

2

Add sequential IDs

Insert <cbc:ID>1</cbc:ID>, <cbc:ID>2</cbc:ID>, etc. as the first child of each InvoiceLine

3

Verify uniqueness

Each line ID must be unique within the invoice (1, 2, 3... is the common pattern)

Code Example

<cac:TaxCategory>
  <cbc:ID>S</cbc:ID>
  <cbc:Percent>21</cbc:Percent>
  <cac:TaxScheme>
    <cbc:ID>VAT</cbc:ID>
  </cac:TaxScheme>
</cac:TaxCategory>

Technical Details

XPath: /Invoice/cac:InvoiceLine/cbc:ID. The line identifier is a simple sequential number (1, 2, 3...) used for referencing specific items in disputes or corrections.

Common Causes

  • Invoice line ID field not mapped in export template
  • Source system uses row ordering not explicit IDs
  • Export template missing InvoiceLine/ID field
  • Line identifiers not generated by source system
  • ID field present but contains empty or null value

Commonly Seen In

All invoicing software

Frequently Asked Questions

VAT category S (standard rate) must include the applicable percentage.
Add the VAT percentage for standard rate items. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, BR-21 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.
Many instances of BR-21 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including standard rate category must have percent.
BR-21 is commonly seen in exports from All invoicing software. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.

Related Errors

BR-19

Tax category code required

BR-S-08

Standard rate VAT amount missing

Last updated: 16 January 2026

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