The verdict in three sentences
An accounting firm with 15 to 40 staff that tracks time, engagement letters and tax deadlines in spreadsheets leaks 2 to 4 margin points per engagement, because overruns surface too late. Off-the-shelf practice tools cost EUR 40 to 120 per user per month and handle production well, but rarely match the way partners actually steer engagements. A custom tool at EUR 30,000 to 70,000, connected to the existing production software, typically pays back in 12 to 20 months for a 25-person firm.
What each option really costs in 2026
The goal is not to replace the bookkeeping and tax production software. It is the steering layer: who works on which client, for how long, against which fixed fee, and by which deadline. That is where spreadsheets break once a firm passes about fifteen people.
| Option | Upfront cost | Annual cost (25 users) | Set-up time | Engagement steering coverage |
|---|---|---|---|---|
| Spreadsheets + shared calendar | EUR 0 | EUR 0 (but 6 to 10 h/week of re-keying) | Immediate | Low, no real-time view |
| Management module of the production suite | EUR 2,000 to 6,000 configuration | EUR 12,000 to 24,000 | 1 to 2 months | Medium, rigid model |
| Specialist practice management software | EUR 3,000 to 8,000 | EUR 18,000 to 36,000 | 2 to 3 months | Good, limited customisation |
| Custom tool connected to production | EUR 30,000 to 70,000 | EUR 4,000 to 9,000 (hosting, maintenance) | 3 to 5 months | Full, aligned with your methods |
| Custom tool + client portal | EUR 45,000 to 85,000 | EUR 6,000 to 12,000 | 4 to 6 months | Full + document collection |
2026 order of magnitude for a 25-user firm. Licences rise by 3 to 6% a year on average, while maintenance of a custom tool stays flat.
The modules that drive profitability
The gain does not come from the interface but from four specific functions. Each has a measurable effect on margin per engagement.
| Module | Problem solved | Observed gain (order of magnitude) | Indicative budget |
|---|---|---|---|
| Time tracking per engagement | Overruns found at year-end | 1.5 to 2.5 margin points | EUR 8,000 to 15,000 |
| Engagement letters generated and e-signed | Unsigned or outdated letters | 100% of clients covered, lower professional risk | EUR 5,000 to 10,000 |
| Fee and retainer billing | Invoicing delayed by 30 to 60 days | DSO down 15 to 25 days | EUR 6,000 to 14,000 |
| Tax and payroll deadline calendar per client | Missed VAT, corporation tax, payroll filings | Client penalties avoided, calmer teams | EUR 5,000 to 12,000 |
| Client portal (uploads, signatures) | Chasing by email and phone | 3 to 5 h saved per staff member per month | EUR 10,000 to 20,000 |
| Partner dashboard | No consolidated view | Pricing decisions based on data | EUR 4,000 to 9,000 |
The connector to the production software (journal exports, client list, year-end status) usually accounts for 15 to 20% of the budget. It removes double entry and drives staff adoption.
How to scope the project safely
A successful project starts with a 2 to 3 day workshop with the partners and two engagement managers. It fixes the tracked indicators (realisation rate, fees per hour, unbilled WIP), the engagement breakdown (bookkeeping, review, year-end, company secretarial, payroll) and alert rules. The first release, delivered in 6 to 8 weeks, covers time tracking and the dashboard, because it funds the rest.
On compliance, client data stays hosted in the EU, encrypted at rest with access logging, which meets GDPR and professional body expectations. The firm owns the code and the data.
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Claire, partner at a 28-person accounting firm in Dublin, bills EUR 2.6M in fees a year. Her managers discover overruns at year-end. She invests EUR 52,000 in a custom tool (time tracking, engagement letters, billing, dashboard), plus EUR 6,500 a year in maintenance.
- Margin gain assumed: 2 points on EUR 2.6M = EUR 52,000 a year.
- Re-keying avoided: 7 h per week × 46 weeks × EUR 45 hourly cost = EUR 14,490 a year.
- Total annual gain: about EUR 66,500, minus EUR 6,500 maintenance = EUR 60,000 net.
- Payback: 52,000 / 60,000 = about 10.5 months.
FAQ
Do we have to drop our production accounting software?
No. The custom tool connects to your existing software and only handles engagement steering. The connector is 15 to 20% of the budget and removes double entry.
What timeline for a 30-person firm?
Allow 3 to 5 months overall, with a first live release in 6 to 8 weeks. Staff training takes 2 half-days.
Will staff actually log their time?
Adoption exceeds 90% when logging takes under 2 minutes a day, from desktop or mobile. Pre-filling from the calendar helps a lot.
Where is our client data hosted?
In the EU, with a certified host, encryption and daily backups retained for 30 days. The firm owns the data and the source code.
How much is maintenance after go-live?
Between EUR 4,000 and 9,000 a year depending on scope, hosting included. That is usually 2 to 4 times less than off-the-shelf licences for 25 users.
Let's scope your project. Send us your headcount, engagement types and production software: we will price a scope between EUR 30,000 and 70,000 with a 3 to 5 month plan. 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.
