The verdict in three sentences
Connecting your business software to billing and payroll costs between 12,000 and 22,000 EUR in 2026, compliant e-invoicing included. The concrete gain is 8 to 15 accounting hours saved per month thanks to the end of re-keying. With the electronic invoice reform ramping up, connecting to a certified partner dematerialization platform (PDP) is no longer optional: better to anticipate it than to be caught out.
The cost: billing, payroll and e-invoicing
A billing-payroll integration project links three worlds: your business software, a billing tool (Sellsy, Pennylane) and a payroll system (Silae). The e-invoice reform adds a compliance item you cannot skip.
| Item | 2026 range (EUR) | Timeline |
|---|---|---|
| Billing connector (Sellsy / Pennylane) | 4,000 - 7,000 | 2-4 weeks |
| Payroll export (Silae) | 3,500 | 1-2 weeks |
| Compliant e-invoicing (PDP / Chorus Pro) | 3,000 - 6,000 | 2-4 weeks |
| Testing and accounting acceptance | 1,500 - 2,500 | 1-2 weeks |
| Total | 12,000 - 22,000 | 6-12 weeks |
The e-invoicing item is the most sensitive in 2026: the reform progressively requires issuing and receiving electronic invoices through a registered PDP. Integrating this link now avoids an emergency project at the deadline.
E-invoicing timeline and accounting gains
The French electronic invoice reform follows a timeline to anticipate. Here are the milestones to remember and the expected gains from integration.
| Element | 2026 detail (order of magnitude) | Impact |
|---|---|---|
| E-invoice reception | Mandatory for all companies | PDP connection required |
| E-invoice issuance | Phased rollout by company size | Anticipate Factur-X format |
| PDP choice | Registered partner platform | Connection cost included |
| Accounting hours saved | 8-15 h/month | 250-450 EUR/month |
| Data entry error reduction | About -70% | Fewer disputes |
| Collection time | Improved by automation | Stronger cash flow |
Beyond compliance, integration pays an immediate dividend: between 8 and 15 hours of accounting entry disappear each month, and gaps between billing and accounts shrink.
Mini case study
Thierry runs a 25-employee services SME in Marseille. His accountant manually re-enters invoices and payroll data across three tools: about 12 hours per month at 35 EUR loaded cost, meaning 420 EUR monthly, plus regular errors. He invests 17,000 EUR in a Pennylane billing connector, a Silae payroll export and the e-invoice connection. Direct savings reach 5,040 EUR per year, the integration pays back in about 3.4 years on this item alone, but above all he is compliant ahead of the regulatory deadline, without last-minute stress.
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FAQ
Should we wait for the e-invoice deadline to integrate?
No, the opposite. Anticipating the PDP connection avoids an emergency project when the obligation is fully in force. You smooth the cost and test calmly instead of enduring calendar pressure.
Which billing tools are easiest to connect?
Pennylane and Sellsy offer modern, well-documented APIs, which simplifies integration. Older tools without an API require a file-based bridge, more fragile and costlier to maintain.
How does the export to Silae for payroll work?
We generate payroll variables (hours, bonuses, absences) from your business software in the format Silae expects, then automate the import. This removes re-keying and makes payslips more reliable.
What is a PDP and why choose one?
A partner dematerialization platform is a registered operator authorized to issue and receive your compliant electronic invoices. Connecting to a PDP is the technical heart of e-invoice compliance.
How long until we are operational?
Expect 6 to 12 weeks depending on the number of connected tools and the complexity of your billing rules. The e-invoice connection adds testing time with the PDP, to plan in the schedule.
Let's scope your project. Tell us your current tools (billing, payroll, business software) and your invoice volume: we scope the connectors and the e-invoice connection. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
