EN 16931 e-invoice: the format coming for everyone
Short answer: if you invoice businesses or public bodies, it is a matter of when, not if. "E-invoicing" in the regulatory sense doesn't mean emailing a PDF — it means a structured, machine-readable document a computer can post straight into accounting software with nobody retyping a line. The EU's definition of what such an invoice must contain is a standard called EN 16931: already mandatory when selling to government, and being phased in for business-to-business sales country by country, on genuinely different timelines.
What EN 16931 actually is — and what it isn't
EN 16931 isn't a file format. It's a semantic model, published by CEN, of what an electronic invoice must carry and how it reconciles: who sold, who bought, what, at which price, under which tax. Two XML syntaxes implement that same model — UBL 2.1 and UN/CEFACT CII — and a conforming file declares which one it follows, so any system reading it knows how to parse it without guessing.
Where it's already mandatory: selling to government
Directive 2014/55/EU required EU public administrations to receive and process EN 16931-conformant e-invoices, and member states transposed it into national law years ago. This is the settled part of the picture: if you invoice a government body anywhere in the EU, the requirement is already live — worth confirming your invoicing setup covers it rather than assuming it does.
Where B2B is heading — and why no date deserves blind trust
Business-to-business is the faster-moving front. At EU level the direction is mandatory structured e-invoicing plus near-real-time digital reporting for cross-border B2B, under the ViDA reforms — but directives set a floor, not a ceiling, and several member states run their own domestic mandates years ahead of it, on schedules that have already moved more than once.
Some countries additionally layer real-time transaction reporting to the tax authority on top of the invoice format itself — a separate, nationally-defined compliance requirement EN 16931 doesn't cover. Track your own country's mandate directly rather than trusting any date printed on a page — including this one.
Getting ready, regardless of your exact deadline
1
Get your seller details right
2
Confirm your invoicing system can actually export structured data
3
Ask your regular business buyers what they can receive
4
Track your own country's mandate directly
5
Keep the human-readable copy too
How Olmira handles this
Every order in Olmira — from the storefront or a paid booking — can produce both a PDF invoice for the customer and a UBL 2.1 e-invoice XML aligned to the EN 16931 semantic model, downloadable straight from the order. It's the structured-format side of this guide: seller and buyer details, line items, tax breakdown and totals, in a form your accounting tools or a buyer's system can read directly. Invoicing belongs to the order, so it ships with the online store — the Pro plan and above, not the Management add-on on Starter. It covers the EU-wide UBL 2.1 / EN 16931 standard specifically — country-specific real-time reporting layers, where a given country requires them, sit outside what this feature does today.
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Not in the regulatory sense. A PDF is a human-readable document; the mandates in question require a structured, machine-readable file (like UBL 2.1) that a computer can process without anyone retyping it. Most businesses will end up producing both.
The mandates discussed here are B2G (government) and B2B (business-to-business). Consumer-facing (B2C) sales aren't the target of structured e-invoicing requirements — you're welcome to issue one anyway, but you're very unlikely to be required to.
No — they're two different XML syntaxes that can both express the same EN 16931 data model. Which one a given country or trading partner expects can differ, which is exactly why the file states which one it is.
Treat this as "when," not "if," for most EU countries, and a growing number of your business buyers may ask for a structured invoice before your own country mandates one — being able to produce one isn't wasted effort even ahead of a deadline.
No — EN 16931 standardises the invoice's content and structure. Some countries separately require near-real-time transaction reporting to the tax authority, which is a distinct, nationally-defined layer on top, not part of the EN 16931 standard itself.
No, and treat every date on this page as provisional. E-invoicing mandates are one of the fastest-moving areas of EU and national tax law right now — confirm your specific obligations and timeline with your accountant or your national tax authority.