If you've ever sent an XRechnung to a German government agency, or validated a ZUGFeRD invoice against EN 16931, your invoice passed through rules maintained by KoSIT — the Koordinierungsstelle für IT-Standards. Based in Bremen and operated under the auspices of the Bremen Senate Chancellery, KoSIT is Germany's central coordination body for IT standards in public administration.
Who Is KoSIT?
KoSIT was established by the IT Planning Council (IT-Planungsrat) — the joint federal-state body that coordinates IT governance across Germany's 16 Länder and the federal government. It is hosted by the Free Hanseatic City of Bremen and operates with a small, focused team.
Location
Bremen, Germany. Hosted by the Bremen Senate Chancellery (Senatskanzlei).
Team Size
A small team of standards experts, technical architects, and compliance specialists.
Mandate
Coordination of IT standards for German public administration, including e-invoicing, e-government, and data exchange.
International Role
Germany’s Peppol Authority, responsible for certifying and overseeing Peppol Access Points operating in Germany.
XRechnung Stewardship
KoSIT's most visible responsibility is maintaining XRechnung — Germany's Core Invoice Usage Specification (CIUS) of the European standard EN 16931. XRechnung defines the specific business rules, field requirements, and validation logic for e-invoices in Germany.
Biannual Release Cycle
XRechnung is updated twice a year, with new versions published in February and August. Each release may include updated Schematron validation rules, new or modified business rules, and corrections based on real-world usage feedback.
EN 16931 Compliance
XRechnung is a CIUS (Core Invoice Usage Specification) of EN 16931, meaning it’s a constrained subset of the European standard. It doesn’t add fields — it specifies which EN 16931 fields are mandatory, conditional, or unused in the German context.
Dual Syntax Support
XRechnung supports both UBL 2.1 and CII (Cross-Industry Invoice) syntax. KoSIT maintains separate Schematron rulesets for each syntax, ensuring that validation is format-appropriate while enforcing the same business rules.
B2G Mandate
Since November 2020, XRechnung has been mandatory for federal B2G invoices. Länder-level requirements vary — some states mandate XRechnung, others accept additional EN 16931 formats. KoSIT coordinates these rules across jurisdictions.
The Validation Framework
Arguably KoSIT's most impactful contribution is the validation framework. Every compliant e-invoicing solution in Germany should validate invoices against KoSIT's official Schematron rules before submission.
How KoSIT Validation Works
XML Schema Validation
The invoice is first checked against the UBL 2.1 or CII XML schema. This ensures structural correctness — correct element names, data types, and hierarchy.
Schematron Business Rules
The invoice is then validated against KoSIT’s Schematron rules. These are semantic checks — e.g., “if the buyer is in Germany, the VAT ID must start with DE” or “line item totals must equal the invoice total.”
XRechnung CIUS Rules
If the invoice claims XRechnung conformance, additional CIUS-specific rules are applied. These enforce Germany’s specific requirements on top of the base EN 16931 rules.
Validation Report
KoSIT’s tools output a structured validation report showing all errors and warnings, with references to the specific rule IDs and affected XML elements.
Peppol Authority Role
In addition to XRechnung, KoSIT serves as Germany's Peppol Authority — the national body responsible for overseeing the Peppol network within Germany. This role was delegated by OpenPeppol, the international association that governs the Peppol network.
Access Point Certification
KoSIT certifies and oversees Peppol Access Points operating in Germany. Access Points must meet technical requirements, pass interoperability tests, and maintain service level agreements.
Policy Enforcement
As Peppol Authority, KoSIT enforces OpenPeppol’s policies within Germany, including participant registration rules, dispute resolution, and service provider compliance.
SMP Management
KoSIT oversees the German entries in Peppol’s SMP (Service Metadata Publisher) infrastructure, ensuring that German businesses can be discovered and reached via the Peppol network.
Network Monitoring
KoSIT monitors Peppol network traffic within Germany, tracking adoption rates, error rates, and service availability to ensure the network meets quality standards.
Open Source Ethos
One of KoSIT's most distinctive characteristics is its commitment to open-source tooling. Unlike some national standards bodies that keep validation tools proprietary, KoSIT publishes everything openly:
Validation Tool (Open Source)
KoSIT’s validation tool is published on GitHub under an open-source licence. Any e-invoicing platform can integrate it directly into their pipeline.
Schematron Rules (Public)
All XRechnung Schematron validation rules are publicly available. Updated with each biannual release.
Test Invoices (Published)
KoSIT publishes a comprehensive set of test invoices — both valid and intentionally invalid — for testing validation implementations.
Documentation (Public)
Full technical documentation, including field mapping guides, business rule explanations, and migration guides between XRechnung versions.
Practical Implications
For businesses operating in Germany, KoSIT's role has direct practical implications:
- Your e-invoicing solution must validate against the current XRechnung Schematron rules — check for updates every February and August
- If you send B2G invoices, XRechnung conformance is mandatory — KoSIT’s rules are the definitive source
- If you use Peppol in Germany, your Access Point must be KoSIT-certified or work through a KoSIT-certified provider
- KoSIT’s open-source tools can (and should) be integrated into your CI/CD pipeline for automated invoice validation
- When troubleshooting validation errors, reference KoSIT’s published rule IDs — they correspond directly to the Schematron assertions
- Track KoSIT’s biannual releases to stay ahead of rule changes that could affect your invoice generation
KoSIT-Validated E-Invoicing
InvoStaq integrates KoSIT's official validation rules and supports both XRechnung and ZUGFeRD formats for seamless German compliance.