E-invoicing standard and format requirements in 2026-2027
Jun 25, 2026
Driven by a wave of government mandates, the era of emailing PDF invoices is officially coming to a close as businesses transition to digital alternatives.
An e-invoice contains structured, machine-readable data that software can automatically process. E-invoicing standards define what invoice data means and which information must be included, while formats define how that data is technically packaged and exchanged between systems. Together, they determine whether an invoice can be understood and processed by another system.
Yet, adhering to a common standard is only half the battle; without precision, localized discrepancies can still trigger validation failures and payment delays. Telema’s E-invoicing Business Line Manager Heigo Protten explains: “An e-invoice can follow the right standard and still fail validation if local rules, routing identifiers, or ERP field mappings are wrong. It’s often a challenge for businesses to keep those details accurate across countries, networks, and trading partners.”
That is why many rejections stem from missing or incorrect local details rather than from the standard itself. Keeping code lists, validation rules, and routing data accurate for every country and transaction type is the work that e-invoice operators handle, so companies do not have to maintain it in-house.
EN 16931: the European e-invoicing baseline
In Europe, EN 16931 is the key standard for structured e-invoicing. It describes the required business information of an electronic invoice and helps ensure that an invoice created by one organisation can be received and processed by another across countries, sectors, and systems.
The standard began in public procurement and B2G invoicing, where it has long been mandated. The revised EN 16931-1:2025, however, in force since February 2026, is specifically adapted for B2B transactions to support the VAT in the Digital Age (ViDA) initiative. EN 16931 is now the baseline for B2B invoicing in Europe.
EN 16931 is based on a common CORE invoice model that defines the essential information all compliant systems must understand. On top of that, countries and networks can add specific requirements through a CIUS (Core Invoice Usage Specification), which restricts or extends the core model for particular sectors or jurisdictions. Examples include mandatory tax codes, buyer identifiers, or routing references.
As a result, businesses often encounter both a general e-invoicing standard and country-specific profiles. The standard provides the structure, while local implementations define the detailed rules.
ViDA: the driver behind e-invoicing mandates
EN 16931 has been reworked for B2B because ViDA is now EU law. Adopted in March 2025 and in force since April 2025, it sets phased e-invoicing and digital VAT reporting deadlines through 2035.
A few dates matter for any business trading in the EU:
- End of 2026: member states must transpose the ViDA directive into national law.
- January 2030: businesses will no longer need the recipient’s consent to issue an e-invoice.
- July 2030: cross-border intra-EU B2B transactions fall under mandatory e-invoicing and Digital Reporting Requirements (DRR). E-invoices become the default and:
- must comply with EN 16931
- must be issued within 10 days
- must be reported to tax authorities in near real time.
- January 2035: domestic e-invoicing systems that predate 2024, such as Italy’s, must align with the EU model.
One change affects buyers as well as sellers: holding a valid structured e-invoice is set to become a substantive condition for deducting input VAT on eligible intra-EU B2B transactions. Practically, business customers may be unable to reclaim VAT without a compliant e-invoice from you, and large buyers are likely to enforce this in accounts payable before the formal deadline.
National mandates are also outpacing the EU timeline. Belgium has required structured e-invoicing between VAT-registered businesses since January 2026, and France, Germany, Poland, and Romania are phasing in their own rules. For businesses with customers or registrations across the Baltics and the wider EU, the question now is which country applies and when.
The main e-invoicing formats
Several formats can support structured e-invoicing, depending on the country, transaction type, network, and buyer.
Universal Business Language (UBL) is an XML-based format widely used in networks such as Peppol. Its flexible structure supports detailed invoice data, including line items, taxes, delivery information, and payment details, making it well suited to cross-border invoicing and B2B transactions. Because UBL is so detailed, accurate field mapping and valid codes are essential to avoid validation errors.
Cross-Industry Invoice (CII), maintained by UN/CEFACT, is another structured XML format common in EN 16931 implementations. It also serves as the XML component of hybrid formats such as Factur-X and ZUGFeRD. In practice, the choice between UBL and CII is usually driven by the requirements of the receiving network, customer, or authority.
Factur-X and ZUGFeRD are hybrid formats that combine a human-readable PDF with embedded XML data. Finance teams get a familiar visual document; software gets the machine-readable data underneath. This is particularly useful when trading partners have different levels of e-invoicing capability. Hybrid formats remain valid as long as the embedded XML carries the required data structure. Get that wrong and it fails validation like any other format.
Peppol BIS Billing defines how invoices move through the Peppol network in alignment with EN 16931, and is widely used for cross-border B2G and B2B transactions. While Peppol simplifies international connectivity, it does not exempt you from local requirements.
E-invoicing requirements by transaction type
Different transaction types often have different rules. A format that works for one use case may fail in another.
Business-to-government (B2G) transactions typically have the strictest compliance requirements, including specific formats, profiles, routing IDs, and transmission channels. Automated validation rejects anything out of spec.
Business-to-business (B2B) transactions are generally more flexible, though several member states already mandate structured e-invoicing, and ViDA makes it mandatory for cross-border intra-EU trade from 2030. Common exchange methods include Peppol, EDI networks, national platforms, and ERP integrations, and the data is often complex (discounts, multiple currencies, detailed lines).
Business-to-consumer (B2C) stays outside the EU-wide mandate and is usually simpler in structured-data terms, but individual countries may impose reporting requirements, and data privacy and customer experience still need thought.
Choosing the right e-invoicing format
There is no single correct format — only the right one for a given invoice. In practice it comes down to five questions:
- Where is the buyer located?
National rules often determine the accepted format, platform, and validation process. - What type of transaction is it?
B2G, B2B, and B2C transactions may follow different requirements. - Which network or platform is used?
Peppol, national tax portals, EDI networks, and public procurement systems may each require specific profiles. - What does the receiving system support?
Even when two formats are legally valid, the buyer’s system may only accept one. - Which local codes and identifiers are required?
Invoice type, VAT category, routing ID, buyer reference, and scheme identifiers can determine whether an invoice passes validation.
In practice, the receiving system often decides what works. ViDA changes that. Once recipient consent is no longer required, the question becomes whether the invoice meets EN 16931 and the relevant local profile. The requirement stays the same: use the right data and codes. The cost of mistakes will be harder to work around.
The benefits of standardised e-invoicing
Done properly, e-invoicing standards and formats improve both compliance and operational efficiency. Structured invoices:
- reduce manual data entry
- lower the risk of typing errors
- help invoices move faster through approval, payment, and reconciliation processes
- make it easier to archive invoice data and respond to tax reporting requirements
For international companies, standardised e-invoicing also supports scalable expansion and cross-border trade, as businesses can rely on common models and format conversion.
Final thoughts
Even with standards in place, implementation can still be difficult, and ViDA raises the stakes rather than settling them. Formats change, country mandates have different timelines, and trading partners or ERP systems possess different technical capabilities. This creates pressure for finance and IT teams who need to manage the system.
To reduce internal maintenance, many businesses use e-invoicing solutions, like Telema e-invoicing, that handle validation rules, routing data, and local requirements through one reliable connection. A valid e-invoice is only as strong as the data behind it.
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