What does an e-invoice validator check?
A validator for e-invoices checks the format and the business rules of an invoice. It cannot judge whether the service, the amounts and the tax rate match the business transaction.
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What a validator can detect
A validator detects format errors: the XML file cannot be read, violates the structure of its format or is missing from the PDF. It detects business-rule errors with the format's validation rules, for XRechnung for example the EN 16931 rules and the German rules (BR-DE-*).
It detects content errors only if they also violate a business rule. As an example of a content error without a rule violation, the German Federal Ministry of Finance (BMF) names “stating an incorrect tax rate”. Business-rule errors in other content, such as a missing buyer reference, are “irrelevant for VAT purposes” under para. 35a.
Four results in the validation report
| Result | When | Basis |
|---|---|---|
| E-invoice | format and business rules without errors | paras. 6a, 6b |
| E-invoice with errors | business rules violated, errors in the PDF or an outdated specification identifier | paras. 6b, 35a |
| Not an e-invoice | format error or ZUGFeRD profile MINIMUM or BASIC WL | para. 6a; UStAE 14.1 para. 14 sentence 4 |
| Cannot be checked | file rejected for security reasons, such as an encrypted or oversized PDF | invowerk's own classification |
An outdated XRechnung version counts as an “e-invoice with errors”: the BMF refers to EN 16931, not to a version of XRechnung.
The PDF in ZUGFeRD and Factur-X
For ZUGFeRD and Factur-X, invowerk also checks the PDF against the rules of ZUGFeRD 2.5.2: PDF/A-3 or PDF/A-4f, the description of the embedded invoice in the PDF metadata and the name of the embedded XML file. Separate rules apply to invoices between German parties (explanation).
Additional hints from invowerk
Besides the result, invowerk shows hints: its own checks that no validation rule of the format covers. These include the check digits of the IBAN, the Leitweg-ID and the VAT ID number, recalculated amounts and dates. For a PDF, invowerk also compares the amount, invoice number and IBAN with the invoice data. Hints do not change the result.
Limits of every check
The BMF writes in para. 35a: “A validation of the e-invoice does not replace the recipient's obligation to check the invoice for completeness and correctness”. A business may rely on the technical result of a “suitable validation application” if it exercises the due care of a prudent businessperson. “As evidence, it is advisable to keep the validation report.” You can save the invowerk validation report as JSON or print it as a PDF.