EN16931 Validator for UBL, CII and Factur-X

An EN16931 validator checks whether an electronic invoice matches the European semantic standard for e-invoicing. Paste your invoice XML and you get a score, every business rule that passed or failed, and a plain-language fix for each problem, in seconds.

EN16931 is the common core behind the national e-invoice formats used across Europe. UBL, UN/CEFACT CII, the German XRechnung and the French and German Factur-X and ZUGFeRD all build on it. That is why one validator can check every one of them: they share the same mandatory fields, the same VAT breakdown, and the same arithmetic.

What the validator checks

• Header fields such as the specification identifier, invoice number, date and currency.
• Seller and buyer details, including the seller VAT identifier when the invoice is standard rated.
• Invoice lines, each with quantity, unit, net amount and item name.
• The VAT breakdown, one entry per rate.
• The arithmetic rules: line totals, tax amounts and the amount due all have to add up.

Why validate before you send

When an electronic invoice reaches a receiving platform, software reads the file automatically. A missing mandatory field or a total that does not add up gets the invoice rejected, and you often find out days later. A check before you send makes those failures visible immediately, so you fix them once in your own system.

What the score means

The score counts how many of the scored mandatory and calculation rules pass. A high score means the data structure is clean. It is a readiness check, not a statement of legal compliance, and it does not decide your tax obligations. This is not legal advice.

Supported formats

UBL 2.1 invoice and credit note, UN/CEFACT CII, XRechnung in both syntaxes, and the XML extracted from ZUGFeRD or Factur-X PDF files.

Which formats can I validate?

UBL 2.1, UN/CEFACT CII, XRechnung, and the XML inside ZUGFeRD or Factur-X. The validator detects the syntax and applies the same EN16931 rules.

Is the EN16931 validator free?

Yes. You can run several checks a day without an account, and nothing you paste is stored.

Does a green score mean I am compliant?

No. It means the format and arithmetic rules that are checked are satisfied. Legal and tax obligations remain your responsibility.

How many rules do you check?

Around forty of the highest-value EN16931 business rules: mandatory fields, VAT breakdown consistency and the arithmetic that has to add up. See the full list in the business rules reference.