If you invoice any German government authority, you have likely encountered KOSIT validation error BR-DE-2: "The Buyer reference must be present." The cause is almost always a missing or incorrect Leitweg-ID. This article explains exactly what the Leitweg-ID is, why it exists, how to read its format, and how to obtain the correct value for your invoicing recipient.
What Is the Leitweg-ID?
The Leitweg-ID (routing identifier, literally 'routing path ID') is a unique numerical identifier assigned to each German government entity or department that receives electronic invoices. It serves as a routing address within the German government's invoice processing infrastructure, ensuring that your XRechnung reaches exactly the right accounting department rather than being lost in a central mailbox.
In XRechnung, the Leitweg-ID is placed in business term BT-10 (Käuferreferenz / Buyer Reference). This field is mandatory under German XRechnung rules — an invoice without a Leitweg-ID will fail KOSIT validation with a Critical error (BR-DE-2).
The Structure of a Leitweg-ID
A Leitweg-ID consists of three segments separated by hyphens:
- Segment 1 (Area Code / Bereichscode): A numerical code identifying the federal state or area. For example, 04 represents Hamburg, 09 represents Bavaria, and 11 represents Berlin. The code 0 represents federal (Bundesbehörden) entities.
- Segment 2 (Institution Code / Einrichtungscode): A longer numerical code identifying the specific institution or department within the area.
- Segment 3 (Check Digit / Prüfziffer): A two-digit check digit calculated from the preceding segments to verify the Leitweg-ID's integrity.
Example: 04011000-1234512345-06 — This identifies a specific entity in Hamburg (04), with institution code 011000123451234, and check digit 06.
How to Get the Correct Leitweg-ID
The Leitweg-ID is assigned by the receiving government authority — you cannot generate it yourself. Here is how to obtain it:
- Check your contract or purchase order: Government authorities typically include the Leitweg-ID in procurement documents, framework agreements, and purchase orders.
- Check the contracting authority's website: Many federal and state agencies publish their Leitweg-IDs on their official websites under sections like 'Rechnungseingang' or 'E-Rechnung'.
- Search the Leitweg-ID registry: A central registry is available at leitweg-id.de, where you can search by agency name.
- Contact the authority directly: If you cannot find the Leitweg-ID, contact the authority's invoicing or finance department (Rechnungswesen / Buchhaltung).
- Ask your project manager: For existing government contracts, the project manager or contract administrator at the authority will know the correct Leitweg-ID.
Leitweg-ID for Federal vs. State Authorities
Federal authorities (Bundesbehörden) use the ZRE (Zentrale Rechnungseingangsplattform) at xrechnung.bund.de. All federal Leitweg-IDs start with 0-.
State and municipal authorities use either OZG-RE (the federated portal) or their own state-specific portals. Each German state has implemented e-invoicing acceptance to varying degrees. The Leitweg-ID structure is the same across all levels of government.
Common Leitweg-ID Mistakes
- Using an outdated Leitweg-ID: Authorities occasionally change their Leitweg-IDs when departments are reorganized. Always verify the current ID for each invoice cycle.
- Formatting errors: The Leitweg-ID must be entered exactly as provided — including all hyphens. Do not add or remove characters.
- Placing it in the wrong field: The Leitweg-ID belongs in BT-10 (Buyer Reference), not BT-46 (Buyer identifier) or any other field.
- Using a Leitweg-ID for a different department: Large ministries may have multiple Leitweg-IDs for different cost centers. Ensure you use the ID specific to your project.
- Confusing it with the Auftragsnummer: The purchase order number (BT-13) is separate from the Leitweg-ID (BT-10). Both may be required simultaneously.
Frequently Asked Questions
Is the Leitweg-ID required for B2B invoices?
No. The Leitweg-ID is only required for invoices submitted to German government authorities (B2G). For B2B invoices, BT-10 is optional and can be used for other buyer reference numbers such as purchase order numbers or contract references.
What if I use the wrong Leitweg-ID?
If the Leitweg-ID is invalid (fails the check digit verification), KOSIT validation will reject the invoice. If the Leitweg-ID is valid but belongs to the wrong department, the invoice may be accepted by the portal but routed to the wrong recipient — causing payment delays.
Does the Leitweg-ID expire?
Leitweg-IDs can be retired or reassigned when agencies are restructured. For long-running contracts, verify the Leitweg-ID at least once per year or whenever you receive updated contract documents from the authority.