Factur-X vs UBL 2.1 vs CII: Choosing a France E-Invoicing Format
Compare the three authorised French e-invoicing formats: Factur-X, UBL 2.1, and UN/CEFACT CII. See how they differ, when to use each, how an Approved Platform converts between them, and why Complyance makes the choice easy.
Table of Contents
Three formats are authorised for France's e-invoicing mandate. All three are built on the same European standard. All three will get your invoice accepted by the tax administration. So why does anyone agonise over the choice? Because the format you standardise on shapes how your systems integrate, how your teams work, and how much friction you hit when trading with partners who picked a different one.
Under the facturation électronique reform, the French tax authority (DGFiP) requires every issued invoice to travel in one of three authorised structured formats: Factur-X, UBL 2.1, or UN/CEFACT CII. Reception becomes mandatory for everyone from 1 September 2026, and issuance for everyone by 1 September 2027. There is no further delay planned, so the format decision is a now decision.
This guide compares the three side by side: how they are structured, how readable they are, what tooling they need, and which fits which situation. You will also see how an Approved Platform (Plateforme Agréée, or PA) converts between them behind the scenes, and why, with Complyance, you often do not have to pick just one.
The Three Authorised Formats at a Glance
All three formats express the same thing, an EN 16931 invoice, in different ways. Think of EN 16931 as the meaning, and each format as a different language for saying it.
1. Factur-X (hybrid)
A PDF/A-3 file with structured CII XML embedded inside it. Human-readable and machine-readable at once. It is the same specification as Germany's ZUGFeRD 2.x.
2. UBL 2.1 (pure XML)
Universal Business Language 2.1, an OASIS XML standard used widely across Europe, in Peppol networks, and in many public-sector systems. Pure structured data, no visible document. Note that Peppol BIS Billing 3.0 is a profile of UBL 2.1, not a separate format, so if a partner asks for "Peppol", they are asking for a particular flavour of UBL.
3. UN/CEFACT CII (pure XML)
Cross Industry Invoice, a UN/CEFACT XML standard. Also pure structured data. Notably, it is the same syntax that lives inside a Factur-X file. Factur-X is essentially CII XML wrapped in a PDF.
Because they all share the EN 16931 semantic backbone, the choice between them is about ergonomics and ecosystem fit, not about whether the tax authority will accept the invoice. It will, in all three cases. France also became a Peppol Authority on 8 July 2025, which reinforces UBL's relevance for businesses already trading over Peppol.
Comparison: Factur-X vs UBL 2.1 vs CII
| Dimension | Factur-X | UBL 2.1 | UN/CEFACT CII |
|---|---|---|---|
| Underlying syntax | CII XML embedded in PDF/A-3 | OASIS UBL XML | UN/CEFACT CII XML |
| Human-readable? | Yes, visible PDF layer | No, raw XML only | No, raw XML only |
| Machine-readable? | Yes, embedded XML | Yes | Yes |
| File type | Single hybrid file (PDF + XML) | XML file | XML file |
| Based on EN 16931? | Yes (COMFORT profile and up) | Yes | Yes |
| Notable profile | Five profiles (MINIMUM to EXTENDED) | Peppol BIS Billing 3.0 is a UBL profile | Used inside Factur-X internals |
| Ecosystem strength | Strong in France and Germany (ZUGFeRD) | Very strong across EU, Peppol, public sector | Strong in France; used in Factur-X internals |
| Tooling maturity | Needs PDF/A-3 + XML libraries | Broad, mature XML tooling and many SDKs | Mature XML tooling |
| File size | Larger (carries the PDF) | Lean | Lean |
| Best fit | Invoices humans still read; smooth adoption | High-volume system-to-system; Peppol-adjacent flows | System-to-system flows already standardised on CII |
Read the table as a decision aid, not a scoreboard. There is no "winner". There is a best fit for your situation, which the next section unpacks.
A Note on EDIFACT and Peppol
Two common points of confusion are worth settling before you choose:
Peppol BIS Billing 3.0 is not a fourth format. It is a constrained profile of UBL 2.1. If you standardise on UBL, you are already close to Peppol compatibility, and your Approved Platform handles the Peppol-specific rules for you.
EDIFACT is not an authorised French format. Many established EDI shops still exchange invoices in EDIFACT. That is fine internally, but EDIFACT cannot travel through the French flow as-is. Your Approved Platform must convert EDIFACT into one of the three authorised structured formats before transmission. Plan for that conversion step rather than assuming your existing EDIFACT pipeline is compliant on its own.
How to Read the Differences
1. Readability is the biggest practical divide.
Factur-X carries a human-readable PDF. UBL and CII do not. Open one and you see XML tags. If your customers, auditors, or AP teams expect to look at an invoice, the hybrid Factur-X removes friction. If no human ever opens the file, that PDF is just extra weight.
2. File size follows from readability.
Factur-X carries a whole PDF inside every invoice, so files are larger. Across millions of high-volume, machine-only invoices, the leaner UBL or CII can be more efficient to store and transmit.
3. Ecosystem fit matters for who you trade with.
UBL 2.1 dominates Peppol and much of European public procurement, so it is a natural fit if you already trade in those networks. Factur-X is strong in France and Germany. CII is common in system-to-system flows and, of course, lives inside every Factur-X file already.
4. Tooling shapes developer effort.
UBL and CII need standard XML libraries, mature and widely available. Factur-X additionally needs PDF/A-3 handling to embed and extract the XML correctly. None of this is hard when your platform does it for you, which is the point of an Approved Platform.
How an Approved Platform Converts Between Formats
Here is the part that dissolves most of the anxiety: you do not have to match your buyer's format. France's model is deliberately built so that an Approved Platform (PA) can convert between the three authorised formats, because they all encode the same EN 16931 business terms.
The flow works like this:
- You issue in one format.
Your ERP or billing system produces invoices in whichever format is easiest for you, say Factur-X. During the transition period, until December 2027, you may even send a plain PDF for your PA to convert.
- Your PA validates and, if needed, converts.
The PA checks the invoice against EN 16931 and French rules, then converts it to the format the buyer's platform expects, for example UBL 2.1. It also converts non-authorised inputs such as EDIFACT into a compliant structured format.
- The buyer's PA receives it.
Using the PPF Central Directory to locate the buyer's platform, your PA transmits the invoice. The buyer's platform delivers it in whatever form the buyer prefers.
- Meaning is preserved end to end.
Because a field like the buyer SIREN or the invoice total means the same thing across all three syntaxes, conversion does not change the invoice, only how it is written.
Conceptually, a converter maps business terms across syntaxes. For instance, the invoice number (BT-1 in EN 16931) sits in one place in UBL and another in CII, but it is the same value:
EN 16931 business term: BT-1 (Invoice number) = "FR-2026-000123"
UBL 2.1: <cbc:ID>FR-2026-000123</cbc:ID>
CII: <ram:ID>FR-2026-000123</ram:ID>
Factur-X: (same CII <ram:ID>, embedded inside the PDF/A-3)Same value, three homes. A compliant PA knows every mapping, so you standardise internally on one format and still reach every counterparty.
Recommendation Logic: Which Format Should You Pick?
Use this simple decision path to choose your internal standard:
1. Do humans need to read the invoice?
If yes, choose Factur-X (EN 16931 / COMFORT profile). You get compliance plus a readable document, and adoption friction stays low.
2. Are you high-volume, system-to-system, and already in Peppol or public procurement?
If yes, choose UBL 2.1 (which also underpins the Peppol BIS profile). It is lean, mature, and fits the ecosystems you already operate in.
3. Are your systems already standardised on CII?
If yes, choose UN/CEFACT CII. No reason to change what already works; it is a first-class authorised format.
4. Not sure, or you trade with a mix of partners?
Standardise on Factur-X internally and let your PA convert. This is the safest default for most French businesses: your teams keep a readable format, and the platform handles everyone else's preferences.
The honest recommendation for most businesses: start with Factur-X (COMFORT) as your internal standard, and lean on an Approved Platform that converts to UBL 2.1 or CII whenever a counterparty needs it. You get readability, full compliance, and zero format lock-in.
Why Choose Complyance to Handle All Three Formats?
The whole point of an Approved Platform (PA) is that you should not have to become a format expert. Complyance abstracts the choice away.
1. One integration, all three formats
Send Complyance your invoice data in a single structure. It produces Factur-X, UBL 2.1, or CII as needed, and converts between them automatically when a buyer's platform prefers a different one. It also converts non-authorised inputs such as EDIFACT and plain PDFs.
2. Validation before transmission
Every invoice is checked against EN 16931 and French requirements up front. Errors come back in plain language, with the exact field flagged, before anything is sent.
3. Format-agnostic APIs
Your developers do not hand-build XML or PDF/A-3. Clean APIs, a sandbox with test data, and predictable responses let them integrate in days.
4. No lock-in as ecosystems shift
Whether your partners move toward Peppol, UBL, or Factur-X, Complyance adapts the output. Your internal integration stays the same.
5. Ready for what comes next
As France moves toward 2027 and the EU's ViDA reforms reshape cross-border formats, Complyance keeps the mappings current.
Ready to stop worrying about formats?
Complyance lets you standardise on one internal format while staying compatible with every counterparty. Explore Complyance and test all three formats in a sandbox.
Conclusion: Pick a Default, Let the Platform Handle the Rest
The three authorised French formats are three languages for the same EN 16931 invoice. Choosing between them comes down to readability, ecosystem, and tooling, not compliance, because all three comply. Work through this checklist:
- Decide whether humans need to read your invoices (if so, favour Factur-X)
- Check which ecosystems your partners use (Peppol/public sector leans UBL 2.1)
- Remember Peppol BIS is a UBL profile, and EDIFACT must be converted by your PA
- Confirm what your existing systems already produce (CII may already fit)
- Standardise on one internal format to simplify your own systems
- Choose an Approved Platform that converts between all three automatically
- Test conversions in a sandbox before the September 2026 deadline
Pick a sensible default, let your PA do the translating, and the "which format" question stops being a blocker.
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Frequently Asked Questions
France authorises Factur-X (a hybrid PDF/XML file), UBL 2.1 (an OASIS XML standard), and UN/CEFACT CII (a UN/CEFACT XML standard). All three are built on the EN 16931 European semantic standard, so all three are equally valid for the mandate.
Neither is universally better. Factur-X is best when humans still need to read the invoice, because it carries a visible PDF. UBL 2.1 is leaner and dominant in Peppol and public-sector networks, making it strong for high-volume, system-to-system flows. Most French businesses can standardise on Factur-X internally and let their platform convert to UBL when needed.
No. Peppol BIS Billing 3.0 is a profile of UBL 2.1, not a fourth format. If a partner asks for Peppol, they want a specific flavour of UBL, and your Approved Platform handles the Peppol-specific rules. France also became a Peppol Authority on 8 July 2025.
EDIFACT is not an authorised French format. You can keep it internally, but your Approved Platform must convert EDIFACT into one of the three authorised structured formats (Factur-X, UBL 2.1, or CII) before it enters the French flow.
No. An Approved Platform (PA) converts between Factur-X, UBL 2.1, and CII because they all share the EN 16931 semantics. You can issue in one format, and your PA delivers it in whatever format the buyer's platform expects.
No. All three formats are authorised and carry the same EN 16931 data, so the tax administration accepts invoices in any of them. The choice affects integration effort, readability, and ecosystem fit, not acceptance.
About the Author
Swathy
Content Marketer
I’m a Content Marketer at Complyance, focused on e-invoicing. Over the years, I’ve created a wide range of content, including blog posts, whitepapers, and product guides, which have supported Complyance’s growth across markets such as the UAE and EU regions. My goal is to deliver content that is comprehensive, clear, accurate, and easy to understand, no matter how complex the topic.
