# BR-CL-05 VAT accounting 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

> **ERROR**: EN 16931 code-list rule (BR-CL)

## Context and Significance

BT-6 is only needed when VAT must be accounted for in a currency other than the invoice currency, for example an invoice in USD from a seller who declares VAT in EUR. The rule fails when an ERP fills BT-6 by default with a symbol, a currency name or a lowercase code. When BT-6 is present, the VAT total in that currency (BT-111) is also required (BR-53). Example: BT-5 = USD with BT-6 = EUR.

## Solution

If BT-6 is present, set it to a valid ISO 4217 alpha-3 code such as EUR (UBL: cbc:TaxCurrencyCode; CII: ram:TaxCurrencyCode). If VAT is accounted for in the invoice currency, leave BT-6 out.

- [Validate XML](/en/xrechnung-validator?source=resource&rule=BR-CL-05)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&rule=BR-CL-05)

## Valid Examples

- BT-5 = USD, BT-6 = EUR
- BT-6 absent — VAT accounted for in the invoice currency

## 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-04](/resources/kosit-validator-errors/br-cl-04-iso-4217-invoice-currency)
- [BR-53](/resources/kosit-validator-errors/br-53-vat-accounting-currency-total-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.