The dematerialization of invoices in a medium-sized company is not just about installing software and ticking a compliance box. Between auditing existing flows, choosing a platform, migrating supplier data, and training teams, the project involves several departments for months. And the go-live date does not mark the end of the project.
Actual Scope of an Invoice Dematerialization Project
Before discussing duration, it is essential to define what the transition to electronic invoicing actually entails. The scope is not limited to issuing signed PDF files. The reform requires a structured format (Factur-X, UBL, or CII), routing through a partner dematerialization platform (PDP) or the public invoicing portal, and e-reporting for transactions not covered by the standard domestic B2B circuit.
For an SME managing a few hundred invoices per month, this involves mapping current processes: who inputs, who validates, where documents are stored, and which software is involved. This preliminary audit alone takes several weeks because it reveals informal practices (invoices received by email in personal inboxes, missing purchase orders, duplicates between ERP and spreadsheets).
The issue of supplier invoice dematerialization concentrates a significant part of the complexity, as it relates to the relationship with third parties whose sending practices vary considerably.
Three Technical Phases and Their Respective Durations
A dematerialization project is divided into distinct blocks whose durations add up but only partially overlap.
Audit and Framing
This first phase involves cataloging incoming and outgoing flows, identifying stakeholders (accounting, purchasing, finance), and drafting a specifications document. For a medium-sized company, expect between four and eight weeks. The main obstacle is not technical: it is the availability of key individuals, often absorbed by day-to-day management.
Solution Selection and Configuration
Selecting an approved dematerialization platform, negotiating the contract, and then configuring connections with the existing ERP or accounting software represents a second block. The duration depends on the compatibility between existing systems and the chosen solution. When the ERP already has a native connector, configuration can take a few weeks. When a specific interface needs to be developed, this timeframe can easily double.
Testing, Acceptance, and Transition
The testing phase verifies that issued invoices are correctly received by the platform, that mandatory data (SIREN number, VAT mentions, routing identifier) is properly transmitted, and that status returns function correctly. This step generally lasts three to six weeks for an SME, longer if the directory of business partners contains identification errors.
In total, the technical deployment spans three to six months from the start of framing to go-live. This figure assumes a project conducted without major interruptions.
Adjustment Period After the Deployment of Electronic Invoicing
The production start date does not close the project. According to accountants interviewed at the end of August 2026, a three to six month adjustment period is necessary after implementation for companies to stabilize their flows, correct routing errors, and integrate new daily practices.
This post-deployment phase is notably absent from forecast schedules. Content addressing the regulatory timeline stops at the compliance date, as if the transition were instantaneous. In practice, feedback shows three persistent challenges:
- The continuous updating of the customer and supplier directory, as routing identifiers change when a partner migrates to another platform.
- The training of employees who were not involved in the initial project but handle invoices daily (sales assistants, site managers, site supervisors).
- The handling of edge cases: mixed invoices (part domestic B2B, part export), partial credits, deposits, self-billing, which do not always fit into the standard paths configured at the start.
Partial Compliance: The Trap for Companies That Think They Are Ready
A feedback report published by an integrator in August 2026 indicates that some companies that have launched an electronic invoicing project will not be fully compliant with the entire regulatory scope by the deadline. Setting up the issuance of invoices is not enough if the obligation to receive, e-reporting of international operations, or new mandatory mentions are not covered.
This partial compliance mechanically extends the duration of the project. The company thinks it has finished, only to discover gaps in its system when faced with the first real flows. Correcting these discrepancies in production takes longer than addressing them during the acceptance phase because each correction must be validated without interrupting the processing of current invoices.
The official timeline mandates the obligation to receive for all VAT-liable companies by September 1, 2026, followed by the obligation to issue by September 1, 2027, for SMEs and micro-enterprises. The gap between these two dates creates a false impression of leeway. In practice, preparing for receipt without anticipating issuance amounts to redoing the project twice.
Factors That Shorten or Lengthen the Timeline of a Dematerialization Project
Not all projects take the same amount of time. Several factors create significant discrepancies:
- The maturity of the information system: an SME already using a recent cloud ERP with integrated purchasing management will start several weeks ahead of a structure still operating with manually scanned paper invoices.
- The volume of active suppliers: beyond a few hundred suppliers, the creation and verification of the routing directory become a project in itself.
- The involvement of management: projects where the CFO or leader quickly arbitrates technical choices progress significantly faster than those where every decision goes to committee.
- The quality of existing data: incomplete supplier records (incorrect SIREN, outdated address, missing accounting contact) generate cascading blocks during the first submissions.
The total time, from the decision to launch the project to stabilized operation, thus ranges from six months in the best-case scenario to over a year when the company starts with predominantly paper management or discovers compliance gaps late. The dematerialization of invoices is not a sprint toward a regulatory date; it is a process change whose effects are measured well after the technical switch.
