Reference
Markdown exportBT-1 Invoice Number
A unique identification of the Invoice. The identification scheme shall provide uniqueness within the business relationship between the Seller and the Buyer.
BT-1 (Invoice number) is the unique identifier the seller assigns to the invoice. It is mandatory under EN 16931 and German UStG §14, must be unique per supplier per fiscal year, and is the primary key both buyer and tax authorities use to reference the document. Example: 2024-INV-0042.
BT-1 · EN 16931 / XRechnung 3.x
BT Reference Card
Canonical EN 16931 / XRechnung facts for this business term — citable from this anchor.
- BT code
BT-1- Name
- Invoice Number
- Cardinality
- Mandatory (M)
- Business group
- Document
- Data type
- Identifier
- Example value
2024-INV-0042- Common error
- BR-2: An Invoice shall have an Invoice number. The number must be unique per supplier per fiscal year (German UStG §14 sequential numbering).
Quick answer
A unique identification of the Invoice. The identification scheme shall provide uniqueness within the business relationship between the Seller and the Buyer.
Invoice basics
Core document identifiers, dates, process identifiers, and high-level invoice context.
In plain language
A unique identification of the Invoice. The identification scheme shall provide uniqueness within the business relationship between the Seller and the Buyer.
A unique identification of the Invoice. The identification scheme shall provide uniqueness within the business relationship between the Seller and the Buyer.
The invoice number serves as the primary identifier for the invoice and is essential for accounting, payment processing, and legal compliance. It must be unique within the business relationship.
What you usually enter here
Alphanumeric string without spaces or special characters except hyphens
Typical valid values include: INV-2024-001, RE20240327001, R-2024-03-15-001, 2024-INV-12345
Mandatory according to EN 16931-1. German tax law (UStG) requires invoices to have consecutive numbering within one or more series.
What goes wrong often
Avoid values like: , , INV 001, INV/001/2024
Relevant rule codes: BR-2
Examples in context
The invoice number serves as the primary identifier for the invoice and is essential for accounting, payment processing, and legal compliance. It must be unique within the business relationship.
Mandatory according to EN 16931-1. German tax law (UStG) requires invoices to have consecutive numbering within one or more series.
Valid Examples
Use these points as the practical checks for this section.
- INV-2024-001
- RE20240327001
- R-2024-03-15-001
- 2024-INV-12345
- F-20240327-001
Invalid Examples
Use these points as the practical checks for this section.
- INV 001
- INV/001/2024
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-1
Data Type:
text
Cardinality:
1..1
Requirement:
Mandatory
Max Length:
35 characters
Since Version:
XRechnung 1.0+
XML Implementation
/Invoice/cbc:ID/CrossIndustryInvoice/ExchangedDocument/ram:IDValidation Rules
BR-2
BR-2
Why the standard cares about this field
Business Context
The invoice number serves as the primary identifier for the invoice and is essential for accounting, payment processing, and legal compliance. It must be unique within the business relationship.
Legal Requirement
Mandatory according to EN 16931-1. German tax law (UStG) requires invoices to have consecutive numbering within one or more series.
FAQ
Can I use the same invoice number for different customers?
Yes, the invoice number only needs to be unique within the business relationship between you and each specific customer.
What are the requirements for invoice numbering in Germany?
German tax law requires consecutive numbering within one or more series. The numbering system must be designed to prevent gaps and duplicates.