# BR-DE-4 Seller postal code must be provided

The seller's postal code must be provided on the invoice.

## Problem Description

The seller's postal code must be provided on the invoice.

> **ERROR**: XRechnung 3.0

## Context and Significance

German invoice validation expects a complete seller postal address. The postal code is used for address validation and helps avoid ambiguities in city names and locations.

## Solution

Add the seller's postal code to the invoice.

## Valid Examples

- 10115
- 80331
- 20095

## Invalid Examples

- Postal code missing
- Empty <cbc:PostalZone/>

## Code Examples

### Valid XML
```
<cac:AccountingSupplierParty>
  <cac:Party>
    <cac:PostalAddress>
      <cbc:PostalZone>10115</cbc:PostalZone>
    </cac:PostalAddress>
  </cac:Party>
</cac:AccountingSupplierParty>
```

### Invalid XML
```
<cac:AccountingSupplierParty>
  <cac:Party>
    <cac:PostalAddress>
      <!-- Missing cbc:PostalZone -->
    </cac:PostalAddress>
  </cac:Party>
</cac:AccountingSupplierParty>
```

## Technical Details

### Affected Fields
Seller Postal Address, Seller Postal Code

## Related Rules

- [BR-DE-3](/resources/kosit-validator-errors/br-de-3-seller-city-must-be-provided)
- [BR-DE-5](/resources/kosit-validator-errors/br-de-5-seller-country-must-be-provided)

## 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.