The verdict in three sentences
A vertical solution (40-120 EUR/user/month) is unbeatable at the start: fast rollout, regulatory updates included, no technical risk. Custom (35,000-90,000 EUR one-off) becomes rational beyond 25 users, when your processes leave the standard, or when vendor lock-in threatens your agility. The right call rests on three axes: five-year TCO, process fit and integration freedom.
The three decision criteria
Price is only one parameter. A CFO also weighs functional fit (does the software match processes without contortions), payroll and bank integrations, and the degree of vendor dependence.
| Criterion | Vertical solution | Custom |
|---|---|---|
| Upfront cost | Low (subscription) | 35,000 - 90,000 EUR |
| Recurring cost | 40-120 EUR/user/month | 12-18% maintenance/yr |
| Process fit | Imposed standard | 100% tailored |
| Payroll/bank integrations | Depends on connectors | Unlimited (quoted) |
| Regulatory updates | Included | Your responsibility (contract) |
| Vendor lock-in | High | None (owned code) |
Five-year TCO and the tipping point
TCO often decides. Take a vertical solution at 85 EUR/user/month and a custom build at 60,000 EUR + 15% annual maintenance.
| Users | Vertical 85 EUR/user/mo (5 yrs) | Custom 60,000 EUR + 15%/yr (5 yrs) |
|---|---|---|
| 10 | 51,000 EUR | 105,000 EUR |
| 20 | 102,000 EUR | 105,000 EUR |
| 25 | 127,500 EUR | 105,000 EUR |
| 30 | 153,000 EUR | 105,000 EUR |
| 50 | 255,000 EUR | 105,000 EUR |
| 80 | 408,000 EUR | 105,000 EUR |
The tipping point is around 20-22 users. Beyond it the gap widens fast: at 50 users the vertical costs 2.4× more over five years. Add the value of an owned asset and the absence of price-hike risk.
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Mini case study
Claire, CFO of a 45-accounting-user industrial group in Lyon, runs a vertical vendor at 85 EUR/user/month, i.e. 45,900 EUR/year. Missing connectors force re-keying of payroll entries and bank reconciliations: about 3 hours/day of a staff member, i.e. 660 hours/year at 40 EUR loaded = 26,400 EUR. A 60,000 EUR custom build (delivered in 16 weeks) natively integrates payroll and bank and removes that re-keying. Year-1 combined saving: 45,900 EUR subscription + 26,400 EUR time = 72,300 EUR, versus 60,000 EUR + 9,000 EUR maintenance. The project is profitable in the first year.
FAQ
Beyond how many users does custom win? Around 20-25 users over a five-year horizon, depending on your vendor's per-seat price. Below that the vertical solution stays cheaper.
Who handles regulatory updates in custom? Your provider, via a maintenance contract (12-18% of the initial cost per year) covering tax and payroll changes. It's the key point to secure contractually.
Does custom really allow more integrations? Yes, it's its main strength: you connect payroll, banks, ERP and business tools without depending on a vendor's connector catalogue.
How to reduce custom's risk? Require documented code, automated tests, clear IP ownership and a reversibility plan. Phased development also limits budget exposure.
Can we combine both? Yes: keeping a vertical for general accounting and building custom for specific modules (group reporting, integrations) is a common, pragmatic strategy.
Let's scope your project. Share your user count, critical integrations (payroll, bank, ERP) and indicative budget, and we'll model your five-year TCO to decide. 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.
