Public Works Contract: Compliant Electronic Signature in 2026

The building and public works (BTP) sector represents one of the most active sectors in public procurement: in France, public contracts in construction account for over 80 billion euros annually according to data from the Legal Affairs Department (DAJ) of the Ministry of Economy. Yet the complete digitalisation of these procedures remains an ongoing project for many companies in the sector. Since 1 October 2018, public contracts exceeding €25,000 excluding VAT must be mandatorily submitted and processed via electronic platforms. By 2026, regulatory maturity demands reinforced compliance, particularly around qualified electronic signature. This article guides you through legal obligations, best practices and concrete solutions to secure your public works contracts using electronic signature.

Why digitalisation is essential in public works contracts

The regulatory framework imposing digitalisation

The Public Procurement Code (CCP), which came into force on 1 April 2019, consolidated all texts relating to public contracts and concession contracts. It incorporates digitalisation requirements from European Directives 2014/24/EU (public contracts) and 2014/25/EU (special sectors). In practical terms, since 2018 for public buyers and bidding companies, the entire document chain — submission of applications, transmission of technical and administrative documents, signing of commitment acts — must pass through electronic means.

Buyer profiles (platforms of the PLACE, AWS-Achat, Maximilien or e-Bourgogne type) centralise these flows. Article R. 2132-7 of the CCP explicitly specifies that "consultation documents are made available to economic operators on the buyer profile". Electronic signature intervenes at several stages: signature of the commitment act by the successful bidder, signature of amending acts (amendments), and also signature of acceptance reports and work statements in certain contractual configurations.

Specific challenges in the BTP sector

The BTP presents particularities that complicate digitalisation:

• Volume and diversity of stakeholders: a works contract may involve a public client, an architect or engineer, one or several main contractors, declared subcontractors and co-contractors within a temporary grouping of companies (GME).

• Multiple and technical documents: Technical specifications, administrative conditions, DC1, DC2, DC4 forms, tax and social declarations, first-demand bank guarantees (GAPD), execution plans... Each document may require a signature or electronic visa.

• Tight deadlines: open tender procedures impose minimum timeframes for receipt of offers (25 days in standard procedure, reducible under certain conditions). Any delay due to signature malfunctions can result in offer rejection.

To understand the fundamentals before addressing sectoral regulatory aspects, the complete guide to electronic signature sets out the essential terminological and legal foundations.

Levels of electronic signature applicable to public contracts

Simple, advanced or qualified signature: what requirement for BTP?

The eIDAS regulation (No. 910/2014) distinguishes three levels of electronic signature, and French regulation on public contracts does not treat them uniformly. The Order of 12 April 2018 relating to electronic signature in public contracts establishes the applicable technical framework in France.

According to this Order:

• Advanced electronic signature based on a qualified certificate constitutes the minimum level required for signing the commitment act.

• Qualified electronic signature under eIDAS (created using a qualified signature creation device and based on a qualified certificate) offers the presumption of maximum reliability and is recommended for complex contracts or significant amending acts.

It is crucial to understand that simple electronic signature (a simple click or ticked box) is insufficient for contractual documents in public contracts. Certification providers issuing qualified certificates in France are listed on the national trust list (LOTL) published by ANSSI and accessible on the official European Union portal.

For further details on the distinctions between these levels, the guide on eIDAS 2.0 regulation details the changes introduced by the new regulation and their implications for French companies.

Electronic certificates and their compliance

The qualified certificate must be issued by a qualified trust service provider (PSCQ) appearing on the European trust list. In practice, for BTP, this means:

• Obtaining a personal or professional certificate from a PSCQ (ChamberSign, Certigna, DocuSign France, etc.).

• Verifying compatibility of the signature format with buyer profiles: XAdES, CAdES and PAdES formats are most common, in accordance with ETSI EN 319 132 (XAdES) and EN 319 122 (CAdES) standards.

• Configuring the workstation with necessary drivers and middleware, particularly for keys on cryptographic hardware media (USB token or smart card).

One often overlooked point: certificate validity over time. To guarantee the evidential value of signed documents beyond certificate expiration, qualified electronic time stamping is essential. It makes it possible to prove that the signature was affixed at a precise moment when the certificate was valid.

Digitalisation of BTP tender calls: process and best practices

Structuring the documentary flow for bidders

For a BTP company bidding on a public contract, digitalisation requires reviewing internal organisation. Here are the key stages of an optimised process:

Phase 1 — Monitoring and downloading the Call for Competition (DCE): The tender documents are now entirely downloadable from the buyer profile. This stage generally does not require signature but may require registration (account creation) on the platform.

Phase 2 — Preparing application documents: Forms DC1 (letter of application) and DC2 (applicant's declaration) must be completed electronically. Tax declarations (tax compliance, URSSAF certificate) are now issued directly online. Electronic signature for companies covers frequent business use cases, including administrative acts.

Phase 3 — Signing the commitment act: This is the critical stage. The commitment act (AE) or its equivalent in the European Single Procurement Document (ESPD) must be electronically signed by the legal representative of the company or their delegate. In case of a grouping, each member of the grouping signs the DC1 and the lead member signs the AE.

Phase 4 — Submission of the offer: Submission takes place before the deadline date and time indicated in the tender. An electronically timestamped acknowledgement of receipt constitutes proof of timely submission.

Pitfalls to avoid during digitalisation

Experience of public buyers and BTP companies reveals several recurring errors:

• Confusion between delegate signature and individual signature: In a joint or solidarity grouping, only the lead member signs the commitment act. Co-contractors only sign documents directly concerning them (DC1 for each).

• Unsupported signature format: Some buyer profiles do not accept all formats. It is imperative to verify the technical specifications of the tender before proceeding with signing.

• Expired or revoked certificate: Prior verification of certificate status via the OCSP mechanism (Online Certificate Status Protocol) prevents signature rejection.

• Absence of buyer counter-signature: For the contract to be legally formed, the public buyer must also electronically sign the contract and notify the successful bidder. The notification deadline triggers the starting point of contractual obligations.

For companies wishing to assess their return on investment before migrating to a dedicated electronic signature solution, the Certyneo ROI calculator allows you to objectively quantify expected gains based on the volume of documents processed.

Integration of an electronic signature solution into the BTP workflow

Selection criteria for a compliant platform

Faced with the plurality of available solutions on the market, public clients as well as successful bidding companies must select a platform meeting specific criteria for the public contracts context:

• eIDAS compliance: Native support for advanced and qualified signatures, integration with trust service providers referenced on the European trust list.

• Standard signature formats: Support for PAdES for PDFs (most common format in public contracts), XAdES for XML documents, and CAdES for binary files.

• Traceability and audit trail: Detailed audit log, qualified time stamping, archiving compliant with NF Z 42-013 standard.

• Interoperability: Ability to interface with buyer profiles via APIs or standardised exchange protocols.

• Multi-signer management: Essential for groupings of companies or contracts involving multiple levels of internal validation.

The comparative analysis of electronic signature solutions provides a comparative analysis framework of the main available platforms in France, with their respective strengths for B2B and public procurement contexts.

Subcontracting and electronic signature: a chain to secure

Law No. 75-1334 of 31 December 1975 on subcontracting requires prior declaration of subcontractors and approval of their payment terms by the client. In a digitalised context, transmission of the electronically signed DC4 (subcontracting declaration) fits into this legal framework.

Electronic signature also secures:

• Monthly work statements and their transmission for visa to the architect/engineer then payment by the client.

• Acceptance reports (with or without reservations), fundamental acts that trigger the starting point of legal guarantees (completion, two-year and ten-year warranties).

• Amending acts during execution, which must comply with substantive modification thresholds defined in Article R. 2194-1 of the CCP.

Companies already equipped with an existing solution and wishing to benefit from better integration can consult the migration offer to Certyneo for a seamless transition of documentary continuity.

Legal framework applicable to digitalised BTP public contracts

Digitalisation of BTP public contracts falls within a dense legal corpus, articulating national and European law. Here are the fundamental texts that any company in the sector must master.

Public Procurement Code (CCP) — Came into force on 1 April 2019, it codifies Ordinances No. 2015-899 and No. 2016-65. Articles R. 2132-1 to R. 2132-14 govern the methods of making consultation documents available and electronic submission of offers. Article R. 2182-3 requires electronic signature of the commitment act for formalised contracts.

Order of 12 April 2018 — Adopted under Decree No. 2016-360, it clarifies the conditions for using electronic signature in public contracts. It requires use of a qualified certificate under eIDAS regulation and signature formats compliant with ETSI standards.

eIDAS Regulation No. 910/2014 — This European regulation, directly applicable in French law, establishes the legal framework for electronic signatures, electronic seals, electronic time stamps and authentication services. Qualified electronic signature benefits from a presumption of reliability equivalent to handwritten signature (Article 25, paragraph 2). eIDAS 2.0 regulation (EU Regulation 2024/1183), currently being deployed, will strengthen interoperability requirements through the European digital identity wallet (EUDIW).

Civil Code, Articles 1366 and 1367 — Article 1366 establishes the principle of equivalence between electronic and paper writing, provided the author is identified and integrity is guaranteed. Article 1367 defines reliable electronic signature as one "which consists in using a reliable identification process guaranteeing its link with the act to which it attaches".

ETSI Standards — ETSI standards EN 319 132 (XAdES), EN 319 122 (CAdES) and EN 319 102 (PAdES) define the technical profiles of advanced and qualified electronic signatures. They are made mandatory by the 2018 Order for public contracts.

GDPR No. 2016/679 — Digitalisation involves processing personal data (identity of signatories, electronic certificates). Public buyers and platform operators have the status of controllers or processors depending on configurations. Obligations regarding retention periods, access rights and data minimisation apply in full.

NIS 2 Directive (2022/2555/EU) — Transposed into French law by Law No. 2023-703 of 1 August 2023, it requires enhanced cybersecurity requirements for essential and important entities, categories that may include operators of public procurement platforms and certain major BTP clients. Security incidents affecting signature systems must be reported to ANSSI.

Legal risks in case of non-compliance: A signature affixed with a non-qualified certificate or in a non-compliant format may result in offer irregularity and elimination. During execution, a commitment act or amendment signed without complying with regulatory requirements exposes the company to a challenge of the document's evidential value, or even nullity of the act under Articles 1366 and 1367 of the Civil Code.

Usage scenarios: electronic signature in action in BTP

Scenario 1 — A BTP SME managing 40 tender calls per year

An SME specialising in secondary works (around 80 employees, specialising in aluminium joinery and glazing) responded until 2024 to approximately forty public tenders annually by combining paper processes and sending scanned documents. The manager and commercial director had to affix handwritten signatures on the commitment act, scan documents and upload them to buyer profiles, with frequent risk of format errors or deadline breaches.

After deploying a qualified electronic signature solution integrated into their commercial management software, the time for preparing and signing the administrative file fell from 4 hours to less than 45 minutes. Systematic traceability (qualified time stamping, audit log) reduced by 90% disputes over proof of timely submission. The rate of offers rejected for procedural defects fell to zero over the 18 months following deployment.

Scenario 2 — A temporary grouping of companies (GME) for an energy retrofit contract

Three companies — a thermal engineering firm, an external insulation specialist and an electrical contractor — group together in joint GME to bid on a thermal retrofit contract for a social housing portfolio estimated at €3.2 million excluding VAT. The procedure is an open tender subject to CCP with full digitalisation.

The complexity lay in the need to collect DC1 signatures from each of the three members, located in different cities, then signature of the commitment act by the designated lead member. Thanks to an electronic signature platform managing multi-signer workflows with sequencing, the validation circuit was completed in less than 3 working hours, compared to 2-3 days with previous paper or email exchanges. All 47 documents in the file were signed and submitted 72 hours before closure, eliminating any deadline risk.

Scenario 3 — A public client managing notification and execution of works contracts

A local authority managing a multi-year investment programme (approximately twenty active works contracts simultaneously, for an annual volume of around €15 million) undertook to digitalise the entire contractual chain, from notification to acceptance reports.

Before full digitalisation, signing amendments required back-and-forth exchanges between technical department, legal department, the signing elected official and the company. The average processing time for an amendment was 18 working days. After deploying a solution integrating qualified electronic signature and digital signature delegation, this fell to 4 working days, a reduction of 78%. Automatic evidential archiving of signed documents in the authority's document management system further secured preservation of evidence for potential regional audit office reviews.

Frequently Asked Questions

What is the difference between an advanced electronic signature and a qualified signature in a public procurement contract in the construction sector?

An advanced signature based on a qualified certificate is the minimum level required by the order of 12 April 2018 to sign the commitment act of a public procurement contract. A qualified signature under eIDAS goes further: it is created via a certified creation device and benefits from a legal presumption of reliability equivalent to a handwritten signature. It is recommended for complex contracts or financially significant amendments.

Must a subcontractor also have a qualified electronic signature to work on a public procurement contract?

It depends on the documents they are required to sign. The DC4, which formalises the subcontracting declaration, may require a compliant electronic signature if the public buyer mandates it through the buyer's profile. It is therefore advisable for any participant in a temporary grouping of undertakings or any declared subcontractor to obtain a qualified certificate issued by a service provider listed on the national trust list published by ANSSI.

Does an expired electronic certificate retroactively invalidate public procurement contracts already signed?

No, provided that a qualified electronic time stamp was affixed at the time of signature. This mechanism cryptographically fixes the date and time of signature, proving that the certificate was valid at the moment of the act. Without a qualified time stamp, the probative value of the document can be challenged during a dispute or audit, even if the signature itself was compliant at the time of its creation.

What are the risks for a construction company whose bid is signed with a non-compliant electronic signature?

The public buyer is required to declare the bid irregular, which results in its elimination from the procedure, with no possibility of rectification on this point. This inadmissibility is automatic and gives rise to no compensation. In practice, verifying the compliance of the certificate and the compatibility of the signature format (XAdES, CAdES, PAdES) with the buyer's profile used remains a critical step before any bid submission.

Do platforms such as PLACE or Maximilien accept all electronic signature formats?

No, each buyer profile may impose specific technical constraints. The most widely accepted formats are PAdES for PDFs, XAdES for XML files and CAdES for other types of files, in accordance with ETSI standards. Before signing, it is essential to consult the call for competition rules and technical specifications published on the relevant platform, as a format incompatibility may render a document technically unreadable by the buyer.

Conclusion

Digitalisation of public works contracts is no longer optional: it is a structuring regulatory obligation, governed by the Public Procurement Code, eIDAS regulation and the 2018 Order. By 2026, construction companies that have not yet adopted a qualified electronic signature solution face concrete risks: offers rejected for procedural defects, deadlines missed, disputes over the evidential value of contractual acts.

The good news: robust, compliant and easy-to-deploy solutions exist, including for SMEs. They secure each stage — from tendering to work acceptance — whilst significantly reducing administrative timeframes and processing costs.

Certyneo supports you in this transition with an eIDAS-compliant platform, adapted to the multi-signer workflows specific to BTP. Start your free trial or request a demonstration to discover how to effectively digitalise your public contracts.