# BR-DEX-03 Sub invoice line must contain exactly one VAT information

A SUB INVOICE LINE (BG-DEX-01) must contain exactly one SUB INVOICE LINE VAT INFORMATION (BG-DEX-06).

## Problem Description

A SUB INVOICE LINE (BG-DEX-01) must contain exactly one SUB INVOICE LINE VAT INFORMATION (BG-DEX-06).

> **ERROR**: XRechnung 3.0

## Context and Significance

This XRechnung Extension rule only fires in the Extension scenario, which introduces sub invoice lines (UBL cac:SubInvoiceLine) each needing their own single VAT breakdown.

## Solution

Provide exactly one classified tax category (cac:Item/cac:ClassifiedTaxCategory) per SubInvoiceLine, with its VAT category code and rate. If nested lines are unnecessary, the standard XRechnung CIUS profile avoids this Extension rule.

- validate
- convert

## Valid Examples

- SubInvoiceLine with one ClassifiedTaxCategory (S, 19%)

## Invalid Examples

- SubInvoiceLine with no ClassifiedTaxCategory, or with two

## Code Examples

### Valid XML
```
<cac:SubInvoiceLine>
  <cbc:LineExtensionAmount currencyID="EUR">60.00</cbc:LineExtensionAmount>
  <cac:Item>
    <cac:ClassifiedTaxCategory>
      <cbc:ID>S</cbc:ID>
      <cbc:Percent>19</cbc:Percent>
    </cac:ClassifiedTaxCategory>
  </cac:Item>
</cac:SubInvoiceLine>
```

### Invalid XML
```
<cac:SubInvoiceLine>
  <cbc:LineExtensionAmount currencyID="EUR">60.00</cbc:LineExtensionAmount>
  <cac:Item>
    <cbc:Name>Component</cbc:Name>
  </cac:Item>
</cac:SubInvoiceLine>
```

## Affected Fields

- [BG-DEX-01 Sub invoice line](/resources/xrechnung)
- [BG-DEX-06 Sub invoice line VAT information](/resources/xrechnung)

## Related Rules

- [BR-DEX-02](/resources/kosit-validator-errors/br-dex-02-sub-invoice-line-net-amount-sum)
- [BR-DE-21](/resources/kosit-validator-errors/br-de-21-specification-identifier-syntax)

## Validation Tools

- [Official KoSIT Validator](https://erechnungsvalidator.service-bw.de/): Validate your XRechnung files against all BR-DE rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Automatic validation error fixes when converting.

## Related Resources

- [Official Specification](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [Complete Error List](/resources/kosit-validator-errors): Overview of all German XRechnung validation rules.