E-invoice validator: check XRechnung & ZUGFeRD online

What an e-invoice validator does

You’ve created or received an XRechnung or ZUGFeRD file and want to know whether it’s actually correct. That’s exactly what validators are for: tools that check your file against the European standard EN 16931 and display errors before a recipient rejects it. This post explains what such a validation service does, which formats count, what to watch out for in terms of data protection, and how to avoid errors during creation in the first place.
Demand has increased since 2025. In B2B, companies have had to be able to receive e-invoices since January 1, 2025. That means structured files end up in your inbox—files whose correctness you can’t assess with the naked eye. The tool turns a gut feeling into a clear yes or no.

Why visually checking the PDF isn’t enough

A PDF that looks like an invoice is not yet an e-invoice. A real e-invoice consists of structured XML data. With XRechnung, that’s a pure XML file; with ZUGFeRD, the XML is embedded in a PDF/A-3 wrapper. For tax purposes and automated processing, the XML part counts—not the visual representation.

This is exactly where the trap of a purely visual check lies. The PDF can look clean while the code is missing a mandatory field or a value doesn’t match the code list. The eye can’t see such errors; at the recipient, they lead to automatic rejection. The validator reads precisely these structured data and reports what doesn’t fit.

With ZUGFeRD, a second look is worthwhile. Many simple tools only check the embedded XML and certify conformity on that basis. The PDF/A-3 wrapper remains unchecked. A complete check includes both: the XML and the surrounding PDF format.

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What the validator checks: Three levels

The validation runs on three levels that cover different sources of errors.

The first level is the structure. The tool checks against the official schema (XSD) whether the XML file is technically constructed correctly: correct element order, valid data types, no missing fields.

The second level is the business rules. Using Schematron rules in accordance with EN 16931, the service checks the content logic: do the totals add up, is the tax calculation consistent, are the seller and buyer details complete, do the currency codes match.

The third level is format-specific. For XRechnung, additional German rules apply: the CIUS extensions. For ZUGFeRD, the profile used is checked. Whatever tool you use, the official reference is the KoSIT validator, which the federal government provides as the benchmark for XRechnung.

XRechnung, ZUGFeRD and EN 16931: Which formats count

Two formats have become established in Germany. XRechnung is a pure XML format and mandatory for invoices to public administration. ZUGFeRD is a hybrid: a PDF/A-3 file with embedded XML, popular in business between companies. Both are based on the EN 16931 standard. The related format Factur-X corresponds to the ZUGFeRD EN 16931 profile and is validated in the same way. For cross-border exchange, the Peppol network is also used.

If you’re specifically looking for validation for ZUGFeRD, pay attention to the profiles. ZUGFeRD has several levels with different data scope. Only the higher profiles are considered a fully fledged e-invoice.

Which profiles are permitted as an e-invoice and which transitional periods apply should be checked against the current legal situation before making a binding statement. A good tool automatically detects the profile and applies the appropriate rules.

Validate an e-invoice online for free: What to consider for data protection

You can check an e-invoice online for free. Several providers offer an upload field: drag in the file, wait for the validation report, done. For a quick check of individual files, that’s often enough.

One point is easily overlooked. Anyone uploading an invoice is sending real business and personal data to a third-party server. That’s relevant for data protection. Before you use a free tool, clarify two questions: Where is the data processed, and how long is it stored? Reputable providers specify a server location in the EU and delete the file after a short time.

For regular checks or sensitive data, a solution makes sense where processing takes place transparently in Germany or the EU. easybill’s servers are located in Germany, and we work in compliance with the GDPR and GoBD. That way, control over invoice data stays where it belongs.

Common validation errors and what they mean

Most rejections have a few recurring causes. A validator names them specifically, often sorted by severity into error, warning, and notice.

Typical issues are missing mandatory details such as tax number, invoice number, or service date. There are also incorrect values from the stored code lists, for example an invalid currency or tax code. Calculation problems are also common: the sum of the line items doesn’t match the total amount, or the tax amount is not consistent. For invoices to authorities, the correct Leitweg-ID is often missing.

Our guide 10 components of an invoice summarizes which mandatory details belong on an invoice. If you fill in these fields properly from the start, you won’t produce most errors in the first place.

Valid doesn’t mean tax-compliant

A green result is a good sign, but it’s not a free pass. The tool confirms that the format is correct. It does not check whether the invoice is correct in terms of content and tax.

An example: An invoice can be technically error-free and still show the wrong tax rate, contain a typo in the amount, or describe a service that was never actually provided. A format check won’t detect that. Professional and tax responsibility remains with the issuer. That’s why there is no guarantee of 100% acceptance: a clean validation report reduces the risk of rejection, but it doesn’t replace the logic of the recipient’s system. For input tax deduction, what matters in the end is that form and content match.

E-invoice to authorities: Leitweg-ID

If an invoice goes to a public contracting authority (B2G), an additional mandatory field is required: the Leitweg-ID. This unique address of the receiving authority routes the invoice to the right place. In the e-invoice data model, this is the buyer’s identifier, often searched for as “buyer legal registration identifier”. If the Leitweg-ID is missing or incorrectly structured, the validation will reject the invoice.

The federal states implement the B2G topic differently. Baden-Württemberg, for example, operates its own central invoice receipt office for state authorities. Anyone sending an e-invoice there clarifies in advance whether the format and routing ID comply with the state’s requirements. A validator helps with this because it checks the routing ID and the format-specific rules in a single run.