BR-CO-21:Document allowance reason required
Each Document level allowance (BG-20) shall contain a Document level allowance reason (BT-97) or a Document level allowance reason code (BT-98), or both.
Engine Classification
Add default allowance reason code 95 (discount) when both reason text and code are missing
Confidence: 85% · Applied automatically in pipeline
What is BR-CO-21?
BR-CO-21 is a fatal validation rule defined in the EN 16931 specification. It validates the AllowanceChargeReasonCode element 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: //cac:AllowanceCharge[cbc:ChargeIndicator='false' and not(cbc:AllowanceChargeReason) and not(cbc:AllowanceChargeReasonCode)]/cbc:AllowanceChargeReasonCode
Why This Error Matters
Invoice rejected. Buyers must understand what discounts are for.
BR-CO-21 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-21
- ·Specification: EN 16931
How to Fix It
Add reason code
Add AllowanceChargeReasonCode (BT-98) with a valid UNCL-5189 code like 95 (Discount)
Or add reason text
Alternatively, add AllowanceChargeReason (BT-97) with descriptive text
Verify placement
Ensure reason is within the same AllowanceCharge element at document level
Before / After
<Invoice> <cac:AllowanceCharge>INVALID_CODE</cac:AllowanceCharge> </Invoice>
<Invoice> <cac:AllowanceCharge>VALID_CODE</cac:AllowanceCharge> </Invoice>
Technical Reference
//cac:AllowanceCharge[cbc:ChargeIndicator='false' and not(cbc:AllowanceChargeReason) and not(cbc:AllowanceChargeReasonCode)]/cbc:AllowanceChargeReasonCodeCommon Causes
- ·Document allowance has no reason text or code
- ·AllowanceCharge missing both reason and reasonCode
- ·Discount added without explanation
- ·Template missing allowance reason fields
- ·Generic allowance applied without categorization
Seeing this in production? The API handles BR-CO-21 automatically. See the fix response →
Frequently Asked Questions
BR-CO-21 occurs when a document level allowance (discount) exists but has no reason code (BT-98) or reason text (BT-97) explaining what the allowance is for.
Add either AllowanceChargeReasonCode with a valid UNCL-5189 code (e.g., 95 for Discount) or AllowanceChargeReason with descriptive text. Invoice Navigator can fix this automatically.
Yes, BR-CO-21 is a business rule violation that will cause invoice rejection. Buyers need to understand what discounts are being applied.
Yes! Invoice Navigator automatically adds the default reason code 95 (Discount) when no reason is provided. This is the standard catch-all discount code from UNCL-5189.
See Also
Related Errors
Last updated: 27 February 2026
Handle BR-CO-21 Automatically in Your Pipeline
The compliance engine auto-remediates this error with controlled safety policies and evidence pack generation.