BR-CO-18:An Invoice shall at least have one VAT breakdown group (BG-23)
Fix: This requires user input to resolve. Provide the correct value for `cac:TaxSubtotal` (BG-23). Provide the required value in the free validator.
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 rejected by Peppol access points and never reaches 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 — the invoice must be corrected and re-sent before it can reach the recipient.
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.
This requires user input to resolve. Provide the correct value for `cac:TaxSubtotal` (BG-23). Invoice Navigator detects this error and prompts for the required business data before applying a safe fix.
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.
BR-CO-18 requires specific business data to resolve. Invoice Navigator detects the error and guides you through providing the needed information, then applies the fix with full audit documentation.
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Last updated: 7 April 2026
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