The verdict in three sentences
The build vs buy decision is a two-signature trade-off: the CFO looks at ROI and TCO, the CTO at feasibility and technical risk. Use a scoring matrix across four axes (core business, differentiation, vendor risk, time to market) to make the choice objective. A build is only justified if break-even falls within the tool's useful life.
The 4-axis decision matrix
Each axis is scored 1 to 5; a high total points toward custom development.
| Decision axis | Weight | Scores toward buy (1-2) | Scores toward build (4-5) |
|---|---|---|---|
| Core business | 30 % | support function | differentiating process |
| Differentiation | 25 % | standard need | competitive advantage |
| Vendor risk | 25 % | solid, stable vendor | hikes / acquisition likely |
| Time to market | 20 % | immediate need | horizon > 6 months acceptable |
A weighted score above 3.5 / 5 justifies the build; below 2.5, buy a SaaS; in between, study the hybrid.
The ROI calculation and break-even
Compare a SaaS at EUR 55,000/year and a build at EUR 140,000 amortised over 4 years, with maintenance of EUR 1,500/month (EUR 18,000/year).
| Horizon | SaaS cumulative | Build cumulative (140k + maint.) | Position |
|---|---|---|---|
| 1 year | EUR 55,000 | EUR 158,000 | SaaS -103,000 |
| 2 years | EUR 110,000 | EUR 176,000 | SaaS -66,000 |
| 2.8 years | EUR 154,000 | EUR 190,400 | nearing break-even |
| 3 years | EUR 165,000 | EUR 194,000 | SaaS -29,000 |
| 4 years | EUR 220,000 | EUR 212,000 | Build +8,000 |
| 5 years | EUR 275,000 | EUR 230,000 | Build +45,000 |
With an 8 %/year SaaS hike, real break-even moves toward 3.3 years instead of 4. The build becomes an amortisable asset and removes pricing risk.
Mini case study
The duo Laurent (CFO) and Nadia (CTO), in a 130-employee B2B services firm in Lyon, must decide on a project-management tool. The target SaaS costs EUR 55,000/year for their 90 users and forces a module billed EUR 9,000. Matrix score: core business 4, differentiation 4, vendor risk 3, time to market 3, i.e. 3.6/5 -> build orientation. Custom development is quoted at EUR 140,000 + EUR 1,500/month. Their break-even lands at 2.8 years; over 5 years they save EUR 45,000 and book a balance-sheet asset. Laurent validates the ROI, Nadia the feasibility: the build launches with a 16-week MVP.
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FAQ
Who decides, the CFO or the CTO?
Both, jointly. The CFO validates ROI and TCO, the CTO feasibility and technical risk. A shared scoring matrix prevents a decision made on a single angle.
What score justifies custom development?
A weighted score above 3.5/5 on the matrix. Below 2.5, SaaS is preferable; in between, a hybrid approach (SaaS + custom module) is often optimal.
How do I compute break-even?
Accumulate the annual SaaS cost and compare it to the build plus its maintenance, year by year. Break-even is the year the two curves cross, here 2.8 to 3.3 years depending on the SaaS hike.
Should I factor in SaaS licence increases?
Yes, absolutely. An 8 %/year hike, common in 2026, pulls the build break-even forward by about a year and often changes the 5-year decision.
What to do with an intermediate score?
Go hybrid: keep the SaaS for standard functions and build custom only the differentiating module. You cap the investment while securing your core business.
Let's scope your project. Send us your scores on the 4 axes and your annual SaaS cost: we compute your score, your break-even and quote the build or the hybrid. 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.
