BR-CO-13:Tax amount calculation error
Fix: Invoice Navigator automatically fixes this issue by correcting the `cbc:TaxExclusiveAmount` element in your Invoice. Upload your invoice to fix this automatically.
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 rejected by Peppol access points and never reaches 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 — the invoice must be corrected and re-sent before it can reach the recipient.
A wrong tax-exclusive total means every downstream calculation (VAT, payable amount) will also be wrong. Tax authorities may flag the invoice for audit.
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.
Related Errors
Related Content
Last updated: 24 April 2026
Validate your invoice
Drop your XML here to check for BR-CO-13
Auto-fix BR-CO-13 in seconds
Upload your invoice and we fix this error automatically. Financial fields are never touched.