BR-CO-18:An Invoice shall at least have one VAT breakdown group (BG-23)
An Invoice shall at least have one VAT breakdown group (BG-23). This applies to the `cac:TaxSubtotal` element in the invoice XML.
Engine Classification
Business data required · Explicit input workflow · No assumptions made
Required input: Invoiced Quantity, Unit Price
What is BR-CO-18?
BR-CO-18 is a fatal validation rule defined in the EN 16931 specification. It validates the LineExtensionAmount element under Invoice > LegalMonetaryTotal 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:LegalMonetaryTotal/cbc:LineExtensionAmount
Why This Error Matters
Invoice rejected. Tax authorities require explicit VAT categorization for all invoices.
BR-CO-18 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-CO-18
- ·Specification: EN 16931
How to Fix It
Sum all lines
Add all InvoiceLine/LineExtensionAmount
Update total
Set LegalMonetaryTotal/LineExtensionAmount to sum
Before / After
<cac:TaxTotal> <cac:TaxSubtotal><!-- invalid or missing value --></cac:TaxSubtotal> </cac:TaxTotal>
<cac:TaxTotal> <cac:TaxSubtotal>correct-value</cac:TaxSubtotal> </cac:TaxTotal>
Technical Reference
XPath: /Invoice/cac:LegalMonetaryTotal/cbc:LineExtensionAmountCommon Causes
- ·Invoice has no VAT breakdown section
- ·TaxTotal/TaxSubtotal elements missing
- ·Tax summary not generated for invoice
- ·Export template missing VAT breakdown section
- ·Zero-tax invoice exported without breakdown
Seeing this in production? The API handles BR-CO-18 automatically. See the fix response →
Frequently Asked Questions
Sum of line net amounts must equal LineExtensionAmount in totals.
Update LineExtensionAmount to match sum of all line amounts. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, BR-CO-18 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-CO-18 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including line extension amount calculation error.
See Also
Related Errors
Last updated: 27 February 2026
Handle BR-CO-18 Automatically in Your Pipeline
The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.