The verdict in three sentences
For a London firm under 8 staff, an off-the-shelf suite at EUR 40-120/user/month is unbeatable on entry cost. Above 12-15 staff, or when your client portal and tax deadlines are a competitive edge, a custom build at EUR 50,000-150,000 pays off over 3-5 years. The real variable is not the sticker price but the 6 to 10 hours per week per person the tool frees up.
Off-the-shelf or custom: the 5-year TCO
The classic trap is comparing a monthly subscription to a one-off development quote. You must reason in total cost of ownership (TCO) over 5 years, including licences, integration, maintenance and training.
| Item (10 staff) | Off-the-shelf | Custom |
|---|---|---|
| Licences / initial dev | EUR 40-120/user/mo | EUR 50,000-150,000 |
| Annual licence cost | EUR 4,800-14,400 | EUR 0 |
| Maintenance/year | included | 12-18 % of dev |
| VAT e-filing integration | often optional | included |
| 5-year TCO (order of magnitude) | EUR 30,000-85,000 | EUR 80,000-210,000 |
| Customisation | limited | full |
Below 10 staff, off-the-shelf almost always wins. Above that, the gap narrows as the per-seat cost bites and customisation gains value.
What makes the functional difference
Every suite handles core bookkeeping. The 2026 differentiation lies in deadline automation and client experience.
| Feature | Firm impact | Estimated gain |
|---|---|---|
| Tax deadline management | Zero VAT/CT/filing misses | -90 % late filings |
| Client portal (document upload) | End of email chasing | 4-6 h/week |
| VAT e-filing integration | Direct submission | 2-3 h/month/client |
| Time tracking per engagement | Bill actuals | +8-15 % billed revenue |
| Profitability dashboard | Loss-making jobs visible | one-click decision |
A client portal that removes the back-and-forth of supporting documents is often the single argument that justifies a custom build on its own.
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Mini case study
Mark, a partner at an 11-staff firm in London, is undecided. A suite at EUR 90/user/month costs him EUR 11,880/year, about EUR 59,400 over 5 years. A custom build at EUR 95,000 amortised over 5 years comes to EUR 19,000/year plus EUR 14,000 maintenance. But his custom client portal frees 7 h/week per staff member; at EUR 45/hour loaded cost, that is 11 x 7 x 45 x 45 weeks, roughly EUR 155,000 of recovered productive capacity per year. Even valuing just 30 % of that gain, the investment is repaid in under 18 months.
FAQ
How much does an accounting suite cost per user in 2026? Expect EUR 40 to 120 per user per month depending on modules (production, payroll, portal). For 10 staff, that is EUR 4,800 to 14,400 per year.
When does custom become worthwhile? Usually above 12 to 15 staff, or when the client portal and deadline automation save more than 6 hours per week per person.
How long does a custom build take? Expect 4 to 8 months for a solid first scope (production, deadlines, portal), with interim releases every 3-4 weeks.
How much does custom maintenance cost? As an order of magnitude, 12 to 18 % of development cost per year, i.e. EUR 6,000 to 27,000 for a EUR 50,000-150,000 project.
Can VAT e-filing be integrated into a custom tool? Yes, e-filing integrates natively and saves 2 to 3 hours per month per client by removing manual entry.
Let's scope your project. Share your headcount, your client portal and tax deadline needs, and an indicative budget. 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.
