The verdict in three sentences
For a practice with 15 to 25 staff, off-the-shelf licences cost 60 to 120 EUR per user per month, or 13,000 to 26,000 EUR a year, and never fit your organisation perfectly. A custom engagement management tool, connected to your existing production software (bookkeeping automation, document management, payroll), costs 40,000 to 80,000 EUR excl. VAT and pays for itself in 24 to 36 months if you recover the margin lost on unprofitable files. The real question is not the price of the tool but how many unbilled hours you lose every month without time tracking per client file.
In London, licence prices are comparable (roughly 50 to 100 GBP per user per month) while development day rates run 20 to 40 % higher than in western France, so the figures below are a conservative baseline.
What a mid-sized practice really pays in 2026
Most mid-sized practices run a stack of tools: a bookkeeping production suite, a spreadsheet for scheduling, a document management system, an engagement letter tool and sometimes a CRM. Each piece works, but nothing links time spent, the billed engagement and the staff member. The result: the partner discovers at year end that 15 to 20 % of files are loss-making.
| Cost item (practice with 18 staff) | Annual cost excl. VAT 2026 | Note |
|---|---|---|
| Bookkeeping production (licences) | 8,600 to 17,300 EUR | 40 to 80 EUR/user/month |
| Document management and archiving | 2,200 to 4,300 EUR | Depends on storage volume |
| Off-the-shelf engagement tool | 4,300 to 8,600 EUR | 20 to 40 EUR/user/month |
| Scheduling spreadsheets (hidden time) | 6,000 to 9,000 EUR | 3 to 4 h/week of manager time |
| Re-keying between tools | 7,500 to 12,000 EUR | 1 to 1.5 h/day combined |
| Total current stack | 28,600 to 51,200 EUR | 2026 order of magnitude |
The hidden cost of re-keying and spreadsheets often exceeds the licence cost. That is where the profitability gain lies.
Custom build or off-the-shelf licences: the numbers
A custom tool does not replace your bookkeeping production software. It sits on top: it orchestrates engagements, consolidates time, calculates profitability per file and feeds billing. It connects to existing tools through APIs or imports.
| Criterion | Off-the-shelf licences | Custom tool |
|---|---|---|
| Upfront investment | 0 to 5,000 EUR (configuration) | 40,000 to 80,000 EUR excl. VAT |
| Recurring cost | 60 to 120 EUR/user/month | 300 to 900 EUR/month (hosting, maintenance) |
| 5-year cost (18 users) | 65,000 to 130,000 EUR | 58,000 to 134,000 EUR |
| Fit with your processes | Partial, set by the vendor | Complete |
| Profitability per file | Often an add-on or limited | Native, real time |
| Connectors (production, DMS, payroll) | Fixed catalogue | Built for your tools |
| Ownership of data and code | Vendor | Practice |
| Time to go live | 1 to 2 months | 4 to 7 months |
Over five years both options converge on cost. The difference is fit: a custom tool follows exactly how you split engagements (bookkeeping, review, payroll, legal, advisory) and your fixed-fee billing rules.
The modules that make the difference
| Module | Indicative budget excl. VAT | Expected gain |
|---|---|---|
| Time tracking per file and engagement | 8,000 to 14,000 EUR | +5 to 8 % billed hours |
| Profitability dashboard per file and client | 6,000 to 12,000 EUR | Spot the 15 % loss-making files |
| Production scheduling (tax deadlines) | 7,000 to 13,000 EUR | Zero missed deadlines |
| Production software and DMS connector | 5,000 to 10,000 EUR | No more re-keying |
| Engagement letters and fee reviews | 4,000 to 9,000 EUR | Evidence-based annual repricing |
| Client portal (documents, questions) | 8,000 to 16,000 EUR | -30 % incoming emails |
A realistic first phase at 40,000 EUR covers time tracking, profitability and the production connector. Other modules follow in iterations.
Mini case study
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Claire, partner in an 18-person practice with 650 client files, bills 2.1 million EUR a year. Her average billed hourly rate is 85 EUR. Analysing three months of logged time, she finds that 14 % of files take 30 % more time than their fixed fee covers.
With a custom tool at 60,000 EUR, she gets real-time profitability per file. She renegotiates 60 fixed fees by +12 % on average (about 50,000 EUR of extra annual revenue) and recovers 1 hour of re-keying per day across the team, worth about 18,000 EUR of productive time. Estimated annual gain: 68,000 EUR. Year 1 cost including maintenance: 67,000 EUR. Payback: 12 months, then roughly 60,000 EUR of net margin per year.
FAQ
Does a custom tool replace my bookkeeping production software?
No. It sits on top of your production software and connects to it. You keep your bookkeeping and review workflow and add a management layer for a budget of 40,000 to 80,000 EUR excl. VAT.
How long does deployment take?
Allow 4 to 7 months for a first phase in production, including 3 to 4 weeks of scoping. The ideal start is after the tax filing peak, to avoid the busiest weeks of the year.
Is my client data protected?
The tool is hosted in the UK or the European Union, with encryption and GDPR-compliant access logs. Professional confidentiality is enforced through access rights per staff member and per file, with hosting at 300 to 900 EUR a month.
Can I finance the project in stages?
Yes, payment is milestone-based, typically 30 % at scoping, 40 % at phase 1 acceptance and 30 % at go-live. Some practices spread phases over two financial years to smooth the investment.
From what size does a custom build make sense?
Below 10 staff, an off-the-shelf licence is usually enough. Above 15 staff or 500 client files, the gain on profitability per file justifies the investment within 12 to 36 months.
Let's scope your project. Engagement mapping, connectors to build, phase 1 between 40,000 and 80,000 EUR excl. VAT, live in 4 to 7 months. 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.
