What Is an E-Invoice? Formats, Rules and Deadlines

Why listen to us: ECIT Digital is a certified Peppol Access Point. We receive e-invoices and read PDFs in the same pipeline for finance teams, so we see both sides of this every day.

Confession: for years I proudly called my PDF invoices "e-invoices", because they arrived by e-mail [polishes PDF lovingly]. The German tax office would like a word. It turns out my beloved PDF is, legally speaking, a picture of an invoice.

If you run finance at a US company, you may wonder why any of this is your problem. Short answer: your European customers and suppliers are now required to use e-invoices, and they are about to ask you for them [phone rings, it is Belgium].

E-invoice vs PDF invoice, at a glance

Both arrive on a screen, which is where the similarity ends [holds the two side by side, squints].

What is an e-invoice?

The EU defines it precisely. Under Directive 2014/55/EU, an electronic invoice is one that "has been issued, transmitted and received in a structured electronic format which allows for its automatic and electronic processing".

The same directive adds, a little coldly, that "a mere image file should not be considered to be an electronic invoice". That is the moment my PDF found out it was adopted [hands PDF a tissue]. Germany's finance ministry says the same in plainer words: a simple PDF no longer counts, because it has no structured format.

The rules for what the data must contain sit in the European standard EN 16931, which describes the core fields every e-invoice carries. Think of it as the recipe, and the formats below as the different kitchens that cook it.

How an e-invoice travels

Most cross-border e-invoices in Europe travel over Peppol, a network where each company connects through an access point. The supplier's access point sends the invoice, the buyer's access point receives and checks it, and the data lands in the buyer's ERP without anyone retyping it.

In Peppol's own words, "Peppol is not a portal, or a provider of exchange services. Peppol is an enabler". It is less like a website and more like a postal system for invoices, with stricter envelopes [licks stamp, regrets it]. One connection to an access point reaches every other company on the network.

E-invoice formats you will run into

An e-invoice is always structured data, but the structure has several names depending on the country and the network. Here are the ones a US finance team is most likely to meet [puts on reading glasses, then a second pair].

Factur-X is the one that confuses people, because it looks exactly like a PDF. It is a PDF that secretly carries the real invoice inside, which is the most my PDF has ever wanted to be [PDF looks hopeful].

E-invoicing regulations by country

E-invoicing regulations usually come in two parts: a date from which companies must be able to receive e-invoices, and a later date from which they must send them. Here is where the main markets stand, from each government's own pages.

If that table made your eyes water, you are reading it correctly [passes the eye drops]. The pattern is simple, though: Europe is moving country by country, and by 2030 cross-border invoices inside the EU will be reported digitally too.

Belgian companies felt it first-hand. On a software forum, one user wrote that "We are a Belgian entity, so this is MANDATORY for us to continue doing business in Belgium from 1 January", before the deadline arrived. For UK specifics, our guide to the UK e-invoicing mandate goes deeper.

The France e-invoicing mandate

France's reform started on 1 September 2026. According to the French government's business portal, every company in France must be able to receive e-invoices from that date, large and mid-sized companies must also issue them, and SMEs and micro-companies must issue them from 1 September 2027.

The tax authority confirms the system is live, with data transmission to the administration "effective since 1 September 2026". If you sell to French companies, expect your customers to ask how you will send invoices from here on. Saying "by email, obviously" is no longer the charming answer it used to be [practices French apology].

Is e-invoicing mandatory in the US?

No. There is no federal or state mandate for e-invoicing between private companies in the US. Federal agencies are a different story: OMB memo M-15-19 directed them to move to "electronic invoicing by the end of FY 2018", mostly through the free Invoice Processing Platform.

For private companies, the Federal Reserve worked with the Business Payments Coalition on a market-ready e-invoice network, which led to the Digital Business Networks Alliance and an exchange framework launched in 2023. It is voluntary, so US adoption moves at the speed of enthusiasm [checks enthusiasm, finds coffee].

Worldwide, Billentis estimates that only 29% of B2B invoices are currently electronic, against 64% in Europe, according to a summary by its sponsor Qvalia. PDFs are not going anywhere soon, and honestly, my PDF is relieved.

What US companies selling to Europe should do

A US company is rarely obliged directly, but its European customers are, so they will start asking for e-invoices. Work through it in this order, ideally before Belgium calls again [unplugs phone].

The receiving side matters too. European suppliers already send structured e-invoices, and taking them over Peppol means no one on your team has to read or retype them, which leaves more time for the things that still arrive as PDFs (hello again, old friend). For the practical side, see how to receive and process e-invoices automatically, or compare the two models in e-invoicing vs traditional invoicing.

Why bother when nobody in the US forces you? Processing cost, mostly. Ardent Partners puts the average cost to process one invoice at $9.90, against $2.67 for Best-in-Class teams, and invoices that never need retyping are a big part of that gap [does the math, smiles for once].

What we see in the field

From inside an access point, e-invoicing looks less like a revolution and more like a long, polite overlap [waves at both formats].

• Every format arrives at once. Peppol e-invoices, PDFs and paper scans land in the same pipeline, and paper is scanned by our partners first.
• E-invoices still get checked. A structured file can carry the wrong VAT number or order reference, so validation does not stop at the format.
• PDFs need a person behind the AI. When our AI is unsure about a field on a PDF, someone on our team checks it, which is how the 99.8% accuracy guarantee holds.
• Clients never touch the document. Clean data goes straight into their ERP, AP workflow tool or property management system.

As for my PDF: it is still here, still loved, and still being read by a very patient AI and a person with coffee [tucks PDF into a folder labeled "legacy"]. It just is not an e-invoice, and now neither of us will pretend otherwise.