The verdict in three sentences
Keeping Cegid or ACD stays the default choice, but a 20-to-40-person firm hitting frozen workflows benefits from building a custom overlay (40,000-90,000 EUR) connected via API. Break-even against licences sits between 3 and 4 years, assuming 15%/yr maintenance. The deciding argument is not price but data ownership, reversibility and the automation the vendor refuses to build.
Vertical licence vs custom build: the real comparison
A vertical suite bills every seat and module; a custom tool is an amortised asset, independent of user count. Here are the 2026 orders of magnitude for a 30-staff firm.
| Criterion | Vertical suite (Cegid/ACD) | Custom module |
|---|---|---|
| Entry cost | 0-5,000 EUR setup | 40,000-90,000 EUR build |
| Annual cost | 40-120 EUR/user/mo = 14,400-43,200 EUR | 15% maintenance = 6,000-13,500 EUR |
| New users | +40-120 EUR/mo each | 0 EUR |
| Workflows | Standard, barely editable | Custom, unlimited |
| Data ownership | Vendor | Firm |
| Reversibility | Constrained export | Owned database and code |
Over 4 years the cumulative comparison narrows, then tips toward custom once headcount passes the break-even threshold.
| Year | Suite (30 users, 65 EUR/mo) | Custom (65k build + 15% maint.) |
|---|---|---|
| Year 1 | 23,400 EUR | 74,750 EUR |
| Year 2 (cumulative) | 46,800 EUR | 84,500 EUR |
| Year 3 (cumulative) | 70,200 EUR | 94,250 EUR |
| Year 4 (cumulative) | 93,600 EUR | 104,000 EUR |
| Year 5 (cumulative) | 117,000 EUR | 113,750 EUR |
The crossover lands around year 5 at constant headcount — but arrives far sooner if the firm hires, since each new seat inflates the licence while costing nothing on the custom side.
What custom really unlocks
The point is not to clone Cegid but to automate what the vendor won't: advanced OCR, smart reminders, specific bank and payroll connectors.
| Automation | Estimated gain | 2026 connector cost |
|---|---|---|
| Invoice OCR + pre-allocation | 1.5 h/file | 6,000-12,000 EUR |
| Automated client reminders | -30% late payments | 3,000-6,000 EUR |
| Multi-bank connector | -2 h/mo/file | 5,000-10,000 EUR |
| Payroll connector (Silae/PayFit) | -1 day/mo payroll | 4,000-8,000 EUR |
| Client portal + e-signature | retention | 5,000-12,000 EUR |
Mini case study
Éric, partner in a 32-person Lyon firm, pays 25,000 EUR/yr in Cegid licences and plans 6 hires over 3 years. Each seat adds 780 EUR/yr of licence, i.e. +14,000 EUR/yr eventually. He commissions a custom overlay at 68,000 EUR + 10,000 EUR maintenance, connected via API to his existing production for OCR and reminders. With 6 recruits, licences would have climbed to 39,000 EUR/yr; the overlay caps at 10,000 EUR/yr. Break-even computed at 41 months, then 29,000 EUR/yr of recurring savings.
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FAQ
Replace everything or plug in an overlay?
In 80% of cases you keep the accounting engine and add an API overlay for automation and the portal. It is lower risk, cheaper (40,000-60,000 EUR) and reversible.
When does custom become profitable?
Between 3 and 5 years at constant headcount, but far sooner while growing: each new user costs 480 to 1,440 EUR/yr of licence versus 0 on custom.
Who owns the data with a custom tool?
The firm owns the database and source code. Reversibility is total, unlike a constrained export from a vendor that often locks the formats.
Is custom 2026 e-invoicing compliant?
Yes, provided it connects to an approved dematerialisation platform. Budget a 2,000-6,000 EUR connector from the spec stage.
What is the main risk of custom?
Vendor dependency. Avoid it with a reversibility clause, documented code delivered and clear 15%/yr maintenance; demand these before signing.
Let's scope your project. Tell us your current suite, headcount and priority automations: we price a reversible API overlay. 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.
