# BR-CL-05 Tax currency code must use ISO 4217 alpha-3

The VAT accounting currency code (BT-6) must be a three-letter code from ISO 4217 alpha-3.

## Problem Description

The VAT accounting currency code (BT-6) must be a three-letter code from ISO 4217 alpha-3.

> **ERROR**: XRechnung 3.0

## Context and Significance

This EN16931 core code-list rule applies when VAT must be reported in a currency different from the invoice currency.

## Solution

When BT-6 is present, set it to a valid ISO 4217 alpha-3 code such as EUR.

- validate
- convert

## Valid Examples

- BT-6 = EUR
- BT-6 = USD

## Invalid Examples

- BT-6 = EURO — invalid ISO 4217 code
- BT-6 = US$ — symbol, not a code

## Code Examples

### Valid XML
```
<cbc:TaxCurrencyCode>EUR</cbc:TaxCurrencyCode>
```

### Invalid XML
```
<cbc:TaxCurrencyCode>EURO</cbc:TaxCurrencyCode>
```

## Affected Fields

- [BT-6 VAT accounting currency code](/resources/xrechnung/bt-6-vat-accounting-currency-code)

## Related Rules

- [BR-CL-03](/resources/kosit-validator-errors/br-cl-03-iso-4217-currency-attribute)
- [BR-CL-04](/resources/kosit-validator-errors/br-cl-04-iso-4217-invoice-currency)

## 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.