Electronically Signed Invoices: Tax Compliance 2026

The digitization of invoices is no longer optional: since the progressive implementation of the electronic invoicing obligation in France, carried by Ordinance No. 2021-1190 of September 15, 2021 and subsequent implementing decrees, companies subject to VAT must issue, transmit and receive their invoices in approved digital formats. Among the central challenges is the digital signature of electronic invoices, guaranteeing authenticity, integrity and tax compliance. This article explores the accepted formats, legal obligations, required signature levels and best practices to adopt to secure your processes in 2026.

Why digital signature is at the heart of electronic invoicing

The Directorate General of Public Finance (DGFiP) imposes three cumulative conditions for an electronic invoice to be fiscally admissible: authenticity of origin, integrity of content and readability of the document (Article 289 of the General Tax Code). Advanced or qualified electronic signature is one of three expressly recognized means to meet these requirements — along with reliable audit trail (PAF) and fiscal EDI.

The three compliance routes according to the CGI

The General Tax Code, in its Articles 289 and 289 bis, clearly distinguishes:

• Advanced electronic signature based on a qualified certificate (in accordance with the eIDAS regulation), which guarantees the identification of the signatory and the integrity of the document since its creation;
• Fiscal EDI (Electronic Data Interchange), governed by strict mutual authentication protocols;
• Reliable audit trail, which requires complete process documentation, often costly to maintain for SMEs.

For the vast majority of companies, digital signature on approved XML formats remains the most legally robust solution and the most technically scalable. It integrates natively into digitized workflows and can be verified automatically by dematerialization partner platforms (PDP) and the Public Invoicing Portal (PPF).

What digital signature concretely guarantees on an invoice

A qualified electronic signature affixed to an invoice guarantees four essential properties:

1. Authenticity: the qualified certificate clearly identifies the invoice issuer;
2. Integrity: any modification after signature is cryptographically detectable;
3. Non-repudiation: the issuer cannot deny having produced the invoice;
4. Timestamping: the date and time of issuance are certified, which can prove decisive in case of tax or commercial dispute.

To deepen the technical and legal foundations, consult our comprehensive guide to electronic signatures, which details the different signature levels and their applications.

XML formats and digital signatures: which to choose in 2026?

The ecosystem of electronic invoicing is based on structured formats whose digital signature must be technically compatible. In 2026, three formats dominate the French and European market.

Factur-X: the Franco-German hybrid reference format

Factur-X (called ZUGFeRD in Germany) is a hybrid PDF/A-3 format integrating a structured XML file (compliant with the EN 16931 standard). It is favored for its dual readability: a PDF readable by humans, an XML processable automatically by ERPs and accounting solutions.

The signature of a Factur-X document is performed by signing the PDF/A-3 container, which simultaneously covers the visual part and the embedded XML flow. The standard ETSI EN 319 132 (XAdES) or ETSI EN 319 122 (CAdES) applies depending on the implementation chosen.

Key data on Factur-X:

• Minimum profile: basic identification data, suitable for micro-enterprises;
• EN 16931 profile (called "Comfort"): complete data compliant with European Directive 2014/55/EU;
• Extended profile: additional data for sectors with high automation needs (distribution, manufacturing).

UBL and CII: European standards to know

Universal Business Language (UBL) and Cross Industry Invoice (CII) are the two XML syntaxes recognized by the European standard EN 16931. The PPF and approved PDPs have accepted these two formats since 2025.

The signature of an invoice in pure UBL or CII XML follows the XAdES (XML Advanced Electronic Signatures) specification, standardized by ETSI. The variant XAdES-B-LT (Long-Term) is recommended to guarantee the verifiability of the signature for the duration of the legal retention period for invoices (10 years in French tax law).

How to choose the right signature level for your invoices?

The eIDAS regulation and its signature levels define three levels: simple, advanced and qualified. For electronic invoices:

• Advanced signature based on a qualified certificate: minimum level recommended by the DGFiP;
• Qualified signature (QES): highest level, incontestable in case of tax or commercial dispute, recommended for high-stakes invoices (public procurement, major accounts, intra-community operations).

Simple signature is not sufficient to meet the requirements of Article 289 CGI.

Tax obligations: what the DGFiP actually controls

Since 2024, the DGFiP has had access to invoicing data via the PPF. Controls focus on several dimensions that digital signature directly secures.

Mandatory data for a compliant electronic invoice

In application of Article 242 nonies A of Appendix II to the CGI, an electronic invoice must include at minimum:

• The SIREN number of the issuer and recipient;
• The nature of operations (delivery of goods, provision of services, mixed operation);
• The payment status;
• The date of delivery or performance of the service.

This data now flows to the administration via the PPF or PDPs. Electronic signature certifies that this data has not been altered between issuance and receipt by the administration.

Retention and archiving of signed invoices

The retention of electronically signed invoices is subject to strict rules:

• 6 years minimum retention for tax audit purposes (Book of Tax Procedures, Article L102 B);
• 10 years in the practice recommended by accountants, consistent with commercial prescription;
• The signature integrity must be verifiable for the entire retention period, which means using signature formats with guaranteed longevity (XAdES-B-LT or XAdES-B-LTA with qualified timestamping).

The qualified electronic timestamping plays a critical role here: it fixes the signature creation date and allows proof that the certificates used were valid at the time of signature, even if those certificates have expired since.

Risks in case of non-compliance

A non-compliant electronic invoice (absence of valid signature, non-approved format, missing data) exposes the company to:

• Rejection of VAT deductibility on corresponding purchases (Article 272 CGI);
• Tax penalties up to €15 per non-compliant invoice, with a minimum of €60 per transaction (Article 1737 CGI);
• A risk of audit adjustment during a tax inspection, if the administration contests the authenticity or integrity of the invoices presented.

Technical integration: connecting signature to your invoicing flows

The major operational challenge of 2026 is the fluid integration of electronic signature into existing processes, without friction for accounting and finance teams.

Signature APIs and ERP connection

Modern electronic signature solutions expose REST APIs allowing automated invoice signing on the fly, directly from ERPs (SAP, Oracle, Sage, Cegid…) or invoicing platforms (Chorus Pro for public procurement, private PDPs for the private sector).

A typical workflow for issuing a signed electronic invoice includes:

1. XML or Factur-X file generation by the ERP;
2. API call to the signature solution (e.g., Certyneo) to affix XAdES-B-LT signature with the company's qualified certificate;
3. Transmission of the signed invoice to the PPF or PDP;
4. Automatic archiving in the digital safe.

Qualified certificates: who issues them and how to obtain them?

In France, qualified electronic signature certificates are issued by Qualified Trust Service Providers (PSCQ) listed on the national trust list (TSL), published and maintained by ANSSI. Among active PSCQs in 2026: Certigna, ChamberSign, Certinomis, as well as European players like Qualified Trust Service Providers referenced in the European Trust List.

Certificates are issued after identity verification of the legal representative or authorized signatory, in-person or by video identification depending on providers. Standard validity period is 1 to 3 years.

To compare available solutions on the market and choose one suited to your invoicing volume, our comparison of electronic signature solutions provides an objective analysis framework based on eIDAS criteria, cost per signature and API integration capabilities.

Sealing vs. signature: a distinction not to be overlooked

In the context of automated invoicing, an important technical distinction applies: electronic signature (commitment of an identified natural person) and electronic seal (commitment of a legal person, without identification of a specific individual). The eIDAS regulation explicitly provides for qualified electronic seals (Article 35 eIDAS) for legal entities.

For electronic invoicing in automated workflows, the qualified electronic seal is often more suitable: it identifies the issuing company without requiring the intervention of an individual signatory for each invoice. The DGFiP recognizes both methods as long as the underlying certificate is qualified under eIDAS.

The legal value of electronic signature in the commercial and tax context is detailed in our dedicated guide, which also addresses the nuances between signature and seal for legal persons.

Applicable legal framework for signed electronic invoices

The compliance of signed electronic invoices relies on a stack of normative texts that are essential to master.

Civil Code, Articles 1366 and 1367: Article 1366 establishes the principle of equivalence between electronic writing and paper writing, provided that the identity of the person from whom it originates is duly assured and that the document is established and retained under conditions to guarantee its integrity. Article 1367 defines electronic signature as the use of a reliable identification process guaranteeing its link with the act to which it attaches.

eIDAS Regulation No. 910/2014 of the European Parliament and Council: This regulation establishes the common legal framework for trust services in the European Union. It defines three signature levels (simple, advanced, qualified), requirements applicable to qualified trust service providers and the legal effects of each signature level. Qualified electronic signature has the legal effect of a handwritten signature in all Member States (Article 25.2 eIDAS). eIDAS 2.0 (Regulation 2024/1183), progressively applicable since 2025, strengthens interoperability requirements and introduces the European digital identity wallet (EUDIW).

General Tax Code, Articles 289 and 289 bis: Article 289 CGI establishes the three compliance routes for electronic invoices (advanced electronic signature with qualified certificate, fiscal EDI, reliable audit trail). Article 289 bis clarifies applicable methods for EDI. Article 242 nonies A of Appendix II lists the 25 mandatory invoice items, several of which are now transmitted electronically to the DGFiP via the PPF.

Book of Tax Procedures, Article L102 B: Requires retention of supporting documents for 6 years from the date they were established or received. For invoices, professionals recommend retention of 10 years consistent with commercial prescription periods (Article L110-4 of the Commercial Code).

Ordinance No. 2021-1190 of September 15, 2021 and implementing decrees: Establish the progressive obligation for electronic invoicing for those subject to VAT established in France, with deployment deadlines between 2026 and 2027 depending on company size.

ETSI EN 319 132 (XAdES) and EN 319 122 (CAdES) standards: European technical standards defining advanced electronic signature formats on XML documents and binary data. The XAdES-B-LT profile is recommended for invoices due to its ability to maintain signature verifiability over the long term.

GDPR No. 2016/679: Personal data contained in invoices (name of individual customer, contact information) is subject to principles of minimization, security and limitation of retention duration. Electronic signature also involves processing of signatory identity data, governed by GDPR and PSCQ certification policies.

Legal and tax risks: An electronic invoice whose signature is invalid, expired or produced with a non-qualified certificate can be requalified by the administration as not meeting the requirements of Article 289 CGI, resulting in rejection of deductible VAT and penalties up to 50% of recalled amounts in case of demonstrated bad faith (Article 1729 CGI).

Use cases: digital signature of invoices in practice

Scenario 1: an industrial SME with high supplier invoice volume

An industrial SME processing approximately 3,500 supplier invoices per year faced two recurring problems: manual validation delays extending the payment cycle to 45 days on average, and occasional VAT deductibility rejections during tax inspections due to invoices received without valid signature or documented audit trail.

By deploying an electronic signature API solution integrated directly into its ERP, the company automated qualified sealing of each issued invoice and implemented automatic validity control of signatures on received invoices. Results observed after 12 months: payment cycle reduction from 45 to 18 days (-60%), zero VAT rejection during the following tax inspection, and estimated 35% savings on administrative invoice processing costs (range consistent with 2025 Gartner sector benchmarks on accounting digitization).

Scenario 2: an accounting firm managing invoicing for 80 SME/SME clients

An accounting firm with about fifteen employees, mandated to manage accounting and produce invoices for each of its client structures, needed to ensure compliance of issued invoices for each legal entity, with distinct certificates per entity.

The firm opted for a multi-entity signature platform allowing management of a portfolio of qualified certificates by client, with complete signature traceability and automatic archiving in individual digital safes. Estimated time savings: 4 to 6 hours per month and per client on manual validation and archiving tasks, representing potential recovery of 320 to 480 hours annually for the firm, reallocated to high-value missions (tax consulting, strategic support).

Scenario 3: a digital services company responding to public contracts

A software services company with about a hundred employees, operating primarily with public sector clients via Chorus Pro, needed to ensure that each issued invoice met the qualified electronic signature requirements imposed by certain public contracting authorities.

By connecting its electronic signature solution to its invoicing tool via REST API, the company now automatically generates invoices in Factur-X format signed with qualified electronic seal, transmitted directly to Chorus Pro. Compliance is verifiable in real time by the contracting authority. No rejections for technical non-compliance have been recorded since production deployment, versus 3 to 4 quarterly rejections previously due to format errors or absence of valid signature. This type of approach is fully consistent with electronic signatures for law firms and service companies, a sector particularly exposed to documentary compliance requirements.

Conclusion

Electronically signed invoices are no longer a topic reserved for IT departments: they are now at the heart of tax and accounting obligations for any company subject to VAT in France. Mastering approved XML formats (Factur-X, UBL, CII), choosing the right signature level (advanced or qualified), and integrating a signature process into your invoicing flows are the three pillars of sustainable compliance in 2026 and beyond.

Qualified digital signature simultaneously guarantees the authenticity of the issuer, the integrity of the data and the tax admissibility of invoices — while reducing processing time and audit adjustment risks.

Certyneo offers a qualified electronic signature API solution natively compatible with Factur-X, UBL and CII formats, integrable in just a few hours into your ERP or PDP. Discover our pricing and start your free trial to secure your electronic invoicing today.