# BR-AE-02 Reverse charge requires seller VAT identifier

Reverse-charge VAT category lines or totals require the seller VAT identifier to be present.

## Problem Description

Reverse-charge VAT category lines or totals require the seller VAT identifier to be present.

> **ERROR**: XRechnung 3.0

## Context and Significance

Reverse charge changes tax liability, so receiving systems need the seller tax identity to audit the treatment.

## Solution

Add the seller VAT registration under the supplier party and keep the reverse-charge category code on the affected lines and VAT breakdown.

- validate
- convert

## Valid Examples

- Seller PartyTaxScheme CompanyID DE123456789 with VAT category AE

## Invalid Examples

- VAT category AE but no supplier VAT registration

## Code Examples

### Valid XML
```
<cac:AccountingSupplierParty>
  <cac:Party>
    <cac:PartyTaxScheme>
      <cbc:CompanyID>DE123456789</cbc:CompanyID>
      <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
    </cac:PartyTaxScheme>
  </cac:Party>
</cac:AccountingSupplierParty>
<cac:TaxCategory>
  <cbc:ID>AE</cbc:ID>
  <cbc:Percent>0</cbc:Percent>
  <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
</cac:TaxCategory>
```

### Invalid XML
```
<cac:AccountingSupplierParty>
  <cac:Party><!-- Missing seller VAT registration --></cac:Party>
</cac:AccountingSupplierParty>
<cac:TaxCategory>
  <cbc:ID>AE</cbc:ID>
  <cbc:Percent>0</cbc:Percent>
  <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
</cac:TaxCategory>
```

## Technical Details

### Affected Fields
BT-31 Seller VAT identifier, BT-151 Invoice line VAT category code

## Related Rules

- [BR-AE-01](#)
- [BR-AE-10](/resources/kosit-validator-errors/br-ae-10-reverse-charge-exemption-reason-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.