# BR-O-09 Not-subject-to-VAT category tax amount must be zero

The VAT category tax amount (BT-117) in a VAT breakdown (BG-23) whose VAT category code (BT-118) is "Not subject to VAT" (O) shall be 0 (zero).

## Problem Description

> **ERROR**: EN 16931 VAT category rule

## Context and Significance

Since category O is outside the scope of VAT, no VAT is due and the category tax amount must be exactly zero. In practice, a VAT amount appears when the software applies a default rate to the O base.

## Solution

Set the O TaxSubtotal cbc:TaxAmount (BT-117) to 0.00.

- [Validate XML](/en/xrechnung-validator?source=resource&rule=BR-O-09)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&rule=BR-O-09)

## Valid Examples

- O breakdown with BT-117 = 0.00

## Invalid Examples

- O breakdown with BT-117 = 5.00

## Code Examples

### Valid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">100.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">0.00</cbc:TaxAmount>
  <cac:TaxCategory><cbc:ID>O</cbc:ID><cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme></cac:TaxCategory>
</cac:TaxSubtotal>
```

### Invalid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">100.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">5.00</cbc:TaxAmount>
  <cac:TaxCategory><cbc:ID>O</cbc:ID><cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme></cac:TaxCategory>
</cac:TaxSubtotal>
```

## Affected Fields

- [BT-117 VAT category tax amount](/resources/xrechnung/bt-117-vat-category-tax-amount)
- [BT-118 VAT category code](/resources/xrechnung/bt-118-vat-category-code)

## Related Rules

- [BR-O-01](/resources/kosit-validator-errors/br-o-01-not-subject-vat-breakdown-required)
- [BR-O-08](/resources/kosit-validator-errors/br-o-08-not-subject-taxable-amount-sum)
- [BR-O-10](/resources/kosit-validator-errors/br-o-10-not-subject-exemption-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.