KoSIT Validator

KoSIT (Koordinierungsstelle für IT-Standards, the German Coordination Office for IT Standards in Bremen) maintains the XRechnung standard on behalf of the federal and state governments. To check e-invoices it publishes its own tool: the KoSIT validator, often called the “KoSIT Prüftool” in German. The source code is public on GitHub at itplr-kosit/validator.

Technically the validator is a generic XML validation engine. It detects the document type, validates it against XML Schema and Schematron, builds a report and computes an acceptance recommendation. What it checks is not hard-coded. It comes from a scenario configuration (scenarios.xml). A scenario says: for this document type, use these schemas, these Schematron files and these report rules.

For XRechnung, KoSIT publishes that configuration separately as validator-configuration-xrechnung. It bundles the UBL 2.1 and CII schemas, the CEN EN 16931 Schematron and the Schematron for the XRechnung CIUS and the XRechnung Extension. Releases are named by date and state the matching XRechnung version, most recently the 3.0 line.

1. Install Java. The standalone JAR runs on Java 11 or later.
2. Download the validator. The itplr-kosit/validator release page has a ZIP with the JAR variants. You need validator-<version>-standalone.jar. Up to version 1.5.0 the file was called validationtool-<version>-standalone.jar; older guides still use that name.
3. Download the XRechnung configuration and unzip it into a folder. It contains scenarios.xml.
4. Validate an invoice:

java -jar validator-<version>-standalone.jar \
  -s <config>/scenarios.xml \
  -r <config> \
  -h invoice.xml

-s points to the scenario file, -r to the folder with the schemas and Schematron (the “repository”). -h writes the HTML part of the report to a file, -p prints the report to the console. You can pass several files at once. --help lists all options.

Daemon mode: with -D the validator starts as an HTTP service. Your application POSTs the XML and gets the report back. Many ERP and accounts-payable systems integrate it this way, so they do not start a new Java process for every invoice.

java -jar validator-<version>-standalone.jar \
  -s <config>/scenarios.xml -r <config> -D

In Java applications you can also embed the validator as a library (Maven coordinates org.kosit:validator).

The validator always writes an XML report. The XRechnung configuration embeds an HTML view in it: the recommendation at the top, then every message with rule ID, severity, text and the XPath of the affected element, followed by a readable rendering of the invoice.

• acceptable: no error that the scenario treats as a reason to reject. Warnings are possible.
• reject: at least one error (schema, or a Schematron rule with level “error”). The receiver may refuse the invoice.

Common reasons for a reject on XRechnung are a missing or wrong Leitweg-ID as buyer reference (BR-DE-15, see Leitweg-ID), missing seller contact details (BR-DE-2, BR-DE-5 to BR-DE-7), a wrong specification identifier in BT-24, or EN 16931 total errors such as BR-CO-15. Our online validator also finds the EN 16931 errors and the BR-DE errors; schema errors only show up in the KoSIT validator.

Online pre-check with our validator when you want to know fast whether an invoice meets the European standard and the XRechnung rules: when you test new invoicing software, answer a customer question, send over Peppol to receivers in other countries, or cannot install Java. You see every error with its rule ID and a fix hint.

KoSIT validator when the invoice goes as XRechnung to a German public body (ZRE, OZG-RE or a state portal), when a receiver explicitly requires XRechnung conformance, or when you need automated validation inside your own system. Only the KoSIT validator with the current configuration also validates the XML Schema and gives the official accept/reject recommendation.

In practice the two work well together: find and fix the EN 16931 and BR-DE errors online first, then run the XRechnung through the KoSIT validator as the final check. More on the formats: XRechnung validator, E-Rechnung validator and ZUGFeRD vs Factur-X vs XRechnung.