# BR-AE-09 Reverse charge VAT category tax amount must be zero

The VAT category tax amount (BT-117) in a VAT breakdown (BG-23) where the VAT category code (BT-118) is "Reverse charge" (AE) shall be 0 (zero).

## Problem Description

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

## Context and Significance

Reverse charge leaves the seller with no output VAT to remit, so the AE category VAT amount must be exactly zero and must not feed the invoice VAT total. In practice, the error occurs when software calculates the standard rate on the AE base and writes that amount into the breakdown.

## Solution

Set the AE cac:TaxSubtotal/cbc:TaxAmount (BT-117) to 0.00; the seller reports no VAT because the buyer accounts for it under the reverse charge mechanism.

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

## Valid Examples

- AE breakdown with BT-118 = AE and BT-117 = 0.00

## Invalid Examples

- AE breakdown with BT-118 = AE but BT-117 = 190.00

## Code Examples

### Valid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">1000.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">0.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>AE</cbc:ID>
    <cbc:Percent>0</cbc:Percent>
    <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
  </cac:TaxCategory>
</cac:TaxSubtotal>
```

### Invalid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">1000.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">190.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>AE</cbc:ID>
    <cbc:Percent>0</cbc:Percent>
    <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-AE-01](/resources/kosit-validator-errors/br-ae-01-reverse-charge-vat-breakdown-required)
- [BR-AE-08](/resources/kosit-validator-errors/br-ae-08-reverse-charge-taxable-amount-sum)
- [BR-AE-10](/resources/kosit-validator-errors/br-ae-10-reverse-charge-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.