# BT-13 Purchase Order Reference

An identifier issued by the buyer for a referenced purchase order. This reference enables automated invoice matching, procurement process tracking, and ensures invoices are linked to authorized purchases.

## Quick answer

An identifier issued by the buyer for a referenced purchase order. This reference enables automated invoice matching, procurement process tracking, and ensures invoices are linked to authorized purchases.

> **Delivery and payment**: Delivery dates, payment means, and the operational context around settlement.

## In plain language

An identifier issued by the buyer for a referenced purchase order. This reference enables automated invoice matching, procurement process tracking, and ensures invoices are linked to authorized purchases.

An identifier issued by the buyer for a referenced purchase order. This reference enables automated invoice matching, procurement process tracking, and ensures invoices are linked to authorized purchases.

Critical for procurement process automation, three-way matching (PO, invoice, receipt), spend analysis, and financial audit trails. Enables automated approval workflows and reduces manual processing errors.

## What you usually enter here

Alphanumeric text with common separators (hyphens, underscores)

Typical valid values include: PO-2025-001234, ORDER_DEF789, B2025/0456, 4711-2025-ABC

Optional but essential for public procurement compliance and corporate governance. Required for many automated procurement systems and ERP integrations.

## What goes wrong often

Avoid values like: , PO, Order123456789012345678901234567890123456789012345678901234567890, PO/001/2025

Relevant rule codes: BR-CO-26

## Examples in context

Critical for procurement process automation, three-way matching (PO, invoice, receipt), spend analysis, and financial audit trails. Enables automated approval workflows and reduces manual processing errors.

Optional but essential for public procurement compliance and corporate governance. Required for many automated procurement systems and ERP integrations.

## Valid Examples

- PO-2025-001234
- ORDER_DEF789
- B2025/0456
- 4711-2025-ABC
- PUR-MUC-2025-001

## Invalid Examples

- PO
- Order123456789012345678901234567890123456789012345678901234567890
- PO/001/2025

## Related Fields

Critical for procurement process automation, three-way matching (PO, invoice, receipt), spend analysis, and financial audit trails. Enables automated approval workflows and reduces manual processing errors.

- [BT-10 Buyer Reference](/resources/xrechnung/bt-10-buyer-reference-leitweg-id)
- [BT-11 Project Reference](/resources/xrechnung/bt-11-project-reference)
- [BT-14 Sales order reference](/resources/xrechnung/bt-14-sales-order-reference)
- [BT-15 Receiving advice reference](/resources/xrechnung/bt-15-receiving-advice-reference)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-13

### Data Type:
text

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
50 characters

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:OrderReference/cbc:ID
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeAgreement/ram:BuyerOrderReferencedDocument/ram:IssuerAssignedID
```

## Validation Rules

### BR-CO-26
BR-CO-26

## Why the standard cares about this field

### Business Context
Critical for procurement process automation, three-way matching (PO, invoice, receipt), spend analysis, and financial audit trails. Enables automated approval workflows and reduces manual processing errors.

### Legal Requirement
Optional but essential for public procurement compliance and corporate governance. Required for many automated procurement systems and ERP integrations.

## FAQ

### Is a purchase order reference always required?
No, the purchase order reference is optional in XRechnung. However, many organizations require it for automated invoice processing and approval workflows.

### What happens if the purchase order reference is incorrect?
An incorrect purchase order reference can cause invoice rejection, delayed payment, or manual processing. It may also prevent three-way matching in automated systems.

### Can multiple invoices reference the same purchase order?
Yes, multiple invoices can reference the same purchase order, especially for partial deliveries or milestone billing. Each invoice typically covers different line items or delivery dates.

### How does purchase order reference affect payment processing?
Purchase order references enable automated validation against approved purchase orders, speed up approval workflows, and ensure payment authorization. Missing references often require manual intervention.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [Invoice Converter](/pdf-to-xrechnung)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)