# BR-CO-23 Line allowance needs a reason or reason code

Each invoice line allowance (BG-27) shall contain an invoice line allowance reason (BT-139) or an invoice line allowance reason code (BT-140), or both.

## Problem Description

> **ERROR**: EN 16931 calculation and consistency rule (BR-CO)

## Context and Significance

This rule is the line-level counterpart of BR-CO-21: every invoice line allowance (UBL: cac:InvoiceLine/cac:AllowanceCharge with cbc:ChargeIndicator = false) needs a reason or a reason code. It does not apply to the item price discount (cac:Price/cac:AllowanceCharge, BT-147), which needs no reason. The error often occurs when a percentage line discount is exported without a description.

## Solution

For every invoice line allowance, add a reason (BT-139) and/or a reason code (BT-140): cbc:AllowanceChargeReason / cbc:AllowanceChargeReasonCode in cac:InvoiceLine/cac:AllowanceCharge in UBL, ram:Reason / ram:ReasonCode in ram:SpecifiedLineTradeSettlement/ram:SpecifiedTradeAllowanceCharge in CII.

- [Validate XML](/en/xrechnung-validator?source=resource&rule=BR-CO-23)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&rule=BR-CO-23)

## Valid Examples

- Line allowance with BT-140 = 95 and BT-139 = "Sample discount"

## Invalid Examples

- Line allowance amount 2.00 with neither BT-139 nor BT-140

## Code Examples

### Valid XML
```
<cac:InvoiceLine>
  <cac:AllowanceCharge>
    <cbc:ChargeIndicator>false</cbc:ChargeIndicator>
    <cbc:AllowanceChargeReasonCode>95</cbc:AllowanceChargeReasonCode>
    <cbc:AllowanceChargeReason>Sample discount</cbc:AllowanceChargeReason>
    <cbc:Amount currencyID="EUR">2.00</cbc:Amount>
  </cac:AllowanceCharge>
</cac:InvoiceLine>
```

### Invalid XML
```
<cac:InvoiceLine>
  <cac:AllowanceCharge>
    <cbc:ChargeIndicator>false</cbc:ChargeIndicator>
    <cbc:Amount currencyID="EUR">2.00</cbc:Amount>
  </cac:AllowanceCharge>
</cac:InvoiceLine>
```

## Affected Fields

- [BG-27 Invoice line allowances](/resources/xrechnung/bt-136-invoice-line-allowance-amount)
- [BT-139 Invoice line allowance reason](/resources/xrechnung/bt-139-invoice-line-allowance-reason)
- [BT-140 Invoice line allowance reason code](/resources/xrechnung/bt-140-invoice-line-allowance-reason-code)

## Related Rules

- [BR-CO-07](/resources/kosit-validator-errors/br-co-07-line-allowance-reason-code-match)
- [BR-CO-21](/resources/kosit-validator-errors/br-co-21-document-allowance-reason-required)
- [BR-CO-24](/resources/kosit-validator-errors/br-co-24-line-charge-reason-required)

## Validation Tools

- [Official KoSIT Validator](https://github.com/itplr-kosit/validator): Run the official KoSIT validator with the XRechnung configuration to check EN 16931 and XRechnung rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Find validation errors during conversion and review each correction.

## Related Resources

- [Official Specification](https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [All validation errors](/resources/kosit-validator-errors): Overview of the EN 16931, XRechnung and Peppol validation rules explained here.