Free E-Invoice Check
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With the introduction of mandatory e-invoicing, technical validation is becoming increasingly important. Our free validator allows you to quickly and easily check e-invoices. Validation is based on EN 16931, the current requirements of the German Federal Ministry of Finance (BMF) and the Peppol BIS Billing 3.0 rules.
✔ Validation according to current legal and technical standards
✔ Immediate error analysis across three validation levels
✔ Display of warnings (anomalies or potential for optimisation that do not render the e-invoice invalid)
The validator checks three categories of errors:
- Format errors (e.g. invalid syntax, incorrect version, unreadable XML)
- Business rule errors (e.g. missing mandatory fields, incorrect codes, incorrect calculation logic)
- Content errors (incomplete or incorrect VAT information)
These three levels correspond to the requirements of EN 16931.
Formally valid but incomplete: Mandatory fields are present but inconsistent.
Incorrect or mixed versions/profiles: Incorrect XRechnung version or incorrect ZUGFeRD profile.
Structural errors: Invalid XML nesting or incorrect data types.
PDF with embedded XML that is not EN 16931-compliant.
FAQ
What is an e-invoice?
An electronic invoice is an invoice that is issued, transmitted and received in a structured electronic format and enables electronic processing.
Which formats qualify as e-invoices?
In Germany, XRechnung and ZUGFeRD invoices using an EN 16931-compliant profile are particularly relevant. What matters is not the format alone, but also the structure, profile and version.
What does EN 16931 mean?
EN 16931 is the European standard that specifies which content and data structures an e-invoice must contain to enable machine processing.
Why do e-invoices need to be validated?
Validation is necessary to ensure that an e-invoice is technically correct in terms of its format, complies with the relevant business rules and is complete in terms of content.
According to the German Federal Ministry of Finance (BMF), validation also helps to mitigate risks relating to input VAT deduction and prevent invoices from being rejected by customers.
Which validation standards apply to e-invoices in Germany?
The requirements of the European standard EN 16931 apply to electronic invoicing in Germany. Three technical formats of e-invoices are relevant:
- UBL (Universal Business Language)
- CII (Cross Industry Invoice)
- ZUGFeRD as a hybrid format (PDF/A-3 with embedded CII/Factur-X XML)
Different validation rules apply depending on the invoice format:
- For CII-based invoices, the EN 16931 CII 1.3.14-2 rule set applies.
- For UBL invoices and credit notes, the OpenPeppol rules (Release 2025.5, BIS Billing 3.0.19) apply.
- ZUGFeRD invoices must be validated in accordance with ZUGFeRD 2.3.3 (EN 16931 profile).
When should an e-invoice be validated?
E-invoices should be validated both before they are sent (outgoing invoices) and when they are received (incoming invoices). Otherwise, errors can result in invoice rejections, delayed payments or time-consuming corrections.
Does the KMLZ E-Invoicing Validator only work for incoming invoices?
No. The KMLZ E-Invoicing Validator can be used both to validate incoming e-invoices and to validate e-invoices generated by your company.
Can I seamlessly integrate the KMLZ E-Invoicing Validator into my invoice processes?
Yes. The KMLZ E-Invoicing Validator can be seamlessly integrated into existing invoice processes. It can be integrated into the customer's system landscape either as Software as a Service (SaaS) or via an on-premises installation.
Does KMLZ provide support with validating e-invoices?
Yes. For technical and content validation, KMLZ provides the E-Invoicing Validator, which automatically identifies typical sources of errors.
We also support companies with the implementation, review and safeguarding of e-invoicing and validation processes, ranging from individual questions to comprehensive end-to-end advice.
