# BR-CL-22 Tax exemption reason code must come from CEF VATEX

The VAT exemption reason code (BT-121) must belong to the CEF VATEX code list.

## Problem Description

The VAT exemption reason code (BT-121) must belong to the CEF VATEX code list.

> **ERROR**: XRechnung 3.0

## Context and Significance

This EN16931 core code-list rule makes the legal basis for an exemption machine-processable across the EU.

## Solution

Set BT-121 to a CEF VATEX code such as VATEX-EU-AE (reverse charge) or VATEX-EU-G (export); the human-readable reason (BT-120) may accompany it.

- validate
- convert

## Valid Examples

- BT-121 = VATEX-EU-AE — reverse charge
- BT-121 = VATEX-EU-G — export outside the EU

## Invalid Examples

- BT-121 = §13b UStG — statute reference, not a VATEX code
- BT-121 = EXEMPT — free text

## Code Examples

### Valid XML
```
<cac:TaxCategory>
  <cbc:ID>AE</cbc:ID>
  <cbc:TaxExemptionReasonCode>VATEX-EU-AE</cbc:TaxExemptionReasonCode>
</cac:TaxCategory>
```

### Invalid XML
```
<cac:TaxCategory>
  <cbc:ID>AE</cbc:ID>
  <cbc:TaxExemptionReasonCode>EXEMPT</cbc:TaxExemptionReasonCode>
</cac:TaxCategory>
```

## Affected Fields

- [BT-121 VAT exemption reason code](/resources/xrechnung/bt-121-vat-exemption-reason-code)

## Related Rules

- [BR-CL-17](/resources/kosit-validator-errors/br-cl-17-uncl5305-document-tax-category)
- [BR-E-01](/resources/kosit-validator-errors/br-e-01-exempt-vat-breakdown-required)
- [BR-AE-02](/resources/kosit-validator-errors/br-ae-02-reverse-charge-seller-vat-id-required)

## 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.