The verdict in three sentences
Paying down technical debt costs between EUR 20,000 and 90,000 depending on scale, but doing nothing costs more in lost velocity and incidents. The right effort is targeted: you pay down the modules that slow you most, not the whole codebase. Fully rewriting a working platform is almost always a mistake at 2 to 3× the budget of a targeted refactoring.
Diagnosis: quantify the debt before acting
Before spending, measure. Debt is quantified through concrete indicators: build time, incident rate, test coverage, average time for a change. Here is a 2026 diagnostic grid.
| Indicator | Healthy platform | High debt |
|---|---|---|
| Test coverage | > 70% | < 30% |
| Time to production | < 30 min | > 2 h |
| Incidents/month | < 3 | > 10 |
| Avg time for a change | 2-5 days | 2-4 weeks |
| Maintenance cost/year | 8-15% of build | > 30% of build |
| New-dev onboarding | < 1 week | > 1 month |
If three or more indicators are in the red, refactoring becomes worthwhile: each month of delay increases the debt's cost.
Prioritisation by module: where to spend
You do not pay it all down at once. Prioritise by impact on velocity and change frequency. Example on a business platform.
| Module | Debt level | Change frequency | Priority | 2026 budget (EUR) |
|---|---|---|---|---|
| Authentication / permissions | High | Medium | High (security) | 8,000 - 18,000 |
| Business core | High | Very high | Critical | 15,000 - 35,000 |
| Reporting / exports | Medium | Low | Low | 4,000 - 10,000 |
| API integrations | High | High | High | 6,000 - 20,000 |
| Admin interface | Low | Low | Deferred | 3,000 - 8,000 |
| Infrastructure / CI-CD | Medium | — | High (cross-cutting) | 5,000 - 15,000 |
Tackle first what is heavily changed AND heavily indebted (business core, integrations): that is where velocity frees up fastest.
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Mini case study
Julie, CTO of a SaaS scale-up in Berlin, faces a platform where every change takes 3 weeks and generates 12 incidents/month. She hesitates between a full rewrite (estimated EUR 220,000, 10 months, frozen-product risk) and targeted refactoring. She picks targeted: business core + integrations + CI/CD, EUR 62,000 over 4 months. Result: change time cut to 5 days (−75%), incidents divided by 3, team velocity +40%. On a team of 5 devs at ~EUR 7,000/month loaded, +40% velocity equals ~2 dev-equivalents gained, i.e. ~EUR 14,000/month of capacity. Effort paid back in ~5 months.
FAQ
When should you rewrite rather than refactor? Almost never while the platform works. A full rewrite costs 2 to 3× a targeted refactoring and freezes the product roadmap for months. Rewrite only if the stack is obsolete and unmaintainable.
How do you justify the budget internally? Cost the debt in lost velocity: if every change takes 3 weeks instead of 5 days, you lose ~70% of dev capacity, i.e. tens of thousands of euros per month on a team of 5.
How long does a refactoring take? 2 to 5 months for a targeted effort, alongside product development (never stop everything). Break into deliverable milestones to measure gains as you go.
What gains should you expect concretely? +30 to +50% velocity, incidents divided by 2 to 3, new-dev onboarding cut by several weeks. These gains appear from the first module treated.
How do you avoid recreating debt? Introduce automated tests (target > 70% coverage), strict CI/CD and code reviews. Without these guardrails, debt returns in 12 to 18 months.
Let's scope your project. Send us your debt indicators (change time, incidents, tests) and a target budget: we prioritise the modules and cost the refactoring. 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.
