# 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

> **ERROR**: EN 16931 core business rule (CEN)

## Context and Significance

This is an EN 16931 core rule. The issue date is the reference point for payment terms, the VAT period and the legal retention period. In UBL the XML schema already rejects a missing or empty cbc:IssueDate, so BR-03 is mostly reported for CII invoices whose date string is exported empty, for example when the date field of the source system is not mapped.

## Solution

In UBL, add cbc:IssueDate in ISO 8601 date format (YYYY-MM-DD). In CII, fill rsm:ExchangedDocument/ram:IssueDateTime/udt:DateTimeString with format="102" (YYYYMMDD). The value must not be empty.

- [Validate XML](/en/xrechnung-validator?source=resource&rule=BR-03)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&rule=BR-03)

## Valid Examples

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

## Invalid Examples

- In CII, udt:DateTimeString (format 102) under ram:IssueDateTime is empty; in UBL a missing or empty cbc:IssueDate is already an XML schema error

## Code Examples

### Valid XML
```
<rsm:ExchangedDocument>
  <ram:ID>RE-2024-0001</ram:ID>
  <ram:IssueDateTime>
    <udt:DateTimeString format="102">20240501</udt:DateTimeString>
  </ram:IssueDateTime>
</rsm:ExchangedDocument>
```

### Invalid XML
```
<rsm:ExchangedDocument>
  <ram:ID>RE-2024-0001</ram:ID>
  <ram:IssueDateTime>
    <udt:DateTimeString format="102"></udt:DateTimeString>
  </ram:IssueDateTime>
</rsm:ExchangedDocument>
```

## 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://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.