# BR-03 Invoice issue date is required

An invoice shall have an Invoice issue date (BT-2) stating the date on which the invoice was issued.

## Problem Description

An invoice shall have an Invoice issue date (BT-2) stating the date on which the invoice was issued.

> **ERROR**: XRechnung 3.0

## Context and Significance

This is a core EN16931 rule; the issue date anchors payment terms, VAT periods and legal retention, so an invoice cannot omit it.

## Solution

Add cbc:IssueDate in ISO 8601 date format (YYYY-MM-DD); it must be present and non-empty.

- validate
- convert

## Valid Examples

- BT-2 = 2024-05-01 — a valid ISO 8601 date

## Invalid Examples

- cbc:IssueDate element is missing from the invoice header

## Code Examples

### Valid XML
```
<cbc:ID>RE-2024-0001</cbc:ID>
<cbc:IssueDate>2024-05-01</cbc:IssueDate>
```

### Invalid XML
```
<cbc:ID>RE-2024-0001</cbc:ID>
<cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
```

## Affected Fields

- [BT-2 Invoice issue date](/resources/xrechnung/bt-2-invoice-issue-date)

## Related Rules

- [BR-02](/resources/kosit-validator-errors/br-02-invoice-number-required)
- [BR-04](/resources/kosit-validator-errors/br-04-invoice-type-code-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.