BR-CO-13:Tax amount calculation error
The VAT amount must equal TaxableAmount × Rate / 100 (with rounding).
Engine Classification
Recalculate TaxExclusiveAmount from sum of line amounts
Confidence: 90% · Applied automatically in pipeline
What is BR-CO-13?
BR-CO-13 is a fatal validation rule defined in the EN 16931 specification. It validates the TaxExclusiveAmount element under 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: /Invoice/cac:LegalMonetaryTotal/cbc:TaxExclusiveAmount
Why This Error Matters
Invoice rejected. Tax exclusive amount is the basis for VAT calculation and must be mathematically correct.
BR-CO-13 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.
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-CO-13
- ·Specification: EN 16931
How to Fix It
Calculate
TaxableAmount × Percent ÷ 100
Round
Round to 2 decimal places (half-up)
Verify total
Sum of TaxAmount must equal TaxTotal
Before / After
<cac:LegalMonetaryTotal> <cbc:TaxExclusiveAmount>999.99</cbc:TaxExclusiveAmount> <!-- Does not match expected calculation --> </cac:LegalMonetaryTotal>
<cac:LegalMonetaryTotal> <cbc:TaxExclusiveAmount>100.00</cbc:TaxExclusiveAmount> <!-- Matches expected calculation --> </cac:LegalMonetaryTotal>
Technical Reference
/Invoice/cac:LegalMonetaryTotal/cbc:TaxExclusiveAmountCode Example
<cac:TaxSubtotal>
<cbc:TaxableAmount currencyID="EUR">1000.00</cbc:TaxableAmount>
<cbc:TaxAmount currencyID="EUR">210.00</cbc:TaxAmount>
<!-- 1000.00 × 21% = 210.00 ✓ -->
<cac:TaxCategory>
<cbc:ID>S</cbc:ID>
<cbc:Percent>21</cbc:Percent>
</cac:TaxCategory>
</cac:TaxSubtotal>Common Causes
- ·Tax exclusive amount calculation incorrect
- ·BT-109 does not equal lines - allowances + charges
- ·TaxExclusiveAmount formula mismatch
- ·Manual total override broke calculation chain
- ·Allowances/charges not factored into subtotal
Seeing this in production? The API handles BR-CO-13 automatically. See the fix response →
Commonly Seen In
Frequently Asked Questions
The VAT amount must equal TaxableAmount × Rate / 100 (with rounding).
Verify TaxAmount = TaxableAmount × Percent ÷ 100. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.
Yes, BR-CO-13 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-13 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including tax amount calculation error.
BR-CO-13 is commonly seen in exports from All invoicing software. These software packages sometimes generate invoices that need adjustment to meet full compliance standards.
See Also
Related Errors
Last updated: 27 February 2026
Handle BR-CO-13 Automatically in Your Pipeline
The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.