The verdict in three sentences
A custom practice management platform for a London accounting firm costs between 40,000 and 100,000 EUR depending on modules (DMS, tax deadline tracker, client portal, time tracking). Off-the-shelf suites are cheaper up front (30-80 EUR/user/month) but drift from your real process and grow expensive over five years. Custom pays off once the firm exceeds 8-10 staff and targets -20% administrative time.
Custom vs licence: the real trade-off
The question is not only the sticker price but process fit and five-year total cost of ownership (TCO). Per-user licensing is comfortable at first but climbs fast with headcount and paid add-ons (portal, e-signature, e-invoicing).
| Criterion | Custom | Off-the-shelf suite |
|---|---|---|
| Upfront cost | 40,000-100,000 EUR | 0-3,000 EUR (setup) |
| Recurring cost | 6,000-14,000 EUR/yr (maintenance) | 30-80 EUR/user/month |
| Process fit | Total | Partial (standard) |
| Code ownership | Firm | Vendor |
| Time to deploy | 4-7 months | 2-6 weeks |
| Extensibility | Unlimited | Vendor roadmap |
Five-year TCO: the tipping point
For a 15-person firm, a 60 EUR/user/month licence already means 10,800 EUR/year, or 54,000 EUR over five years, before add-ons. Custom amortises its build cost and becomes competitive.
| Line item (15-person firm) | Custom 5 yrs | Licence 5 yrs |
|---|---|---|
| Build / setup | 70,000 EUR | 3,000 EUR |
| Recurring | 50,000 EUR | 54,000 EUR |
| Add-ons (portal, e-invoice) | included | 18,000 EUR |
| Admin time saved | -20% | -5% |
| Total TCO (order of magnitude) | 120,000 EUR | 75,000 EUR |
| Value of time saved | +90,000 EUR | +22,000 EUR |
Mini case study
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Claire, partner at a 15-person firm in London, spends a combined 22 h/week on document chasing and time entry. A custom tool at 72,000 EUR (delivered in 6 months) automates the tax deadline tracker and client portal. Estimated gain: -20% administrative time, roughly 230 h/month recovered, valued at 45 EUR/h = ~10,350 EUR/month. The project pays back in 7-8 months.
FAQ
What is the minimum budget to start? A useful core (DMS + time tracking + deadlines) starts around 40,000 EUR. Below that, a configured off-the-shelf suite is wiser.
How long to deliver? Expect 4-7 months depending on modules and integrations (invoicing, 2026 e-invoicing, banking).
Does custom handle 2026 e-invoicing? Yes, integration with mandated formats and approved platforms is designed in; integration budget of 6,000-12,000 EUR per connector.
What concrete time saving? Firms typically see -20% administrative time in year one, mostly on chasing and data entry.
Can we migrate from an existing suite? Yes, client and case data migration is quoted separately: 3,000-9,000 EUR by volume.
Let's scope your project. Tell us your firm size, priority modules, indicative budget (40,000-100,000 EUR) and target date. 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.
