The verdict in three sentences
For a 25-person accounting practice still running engagements on Excel, a custom module for engagement tracking, time recording and engagement letters costs EUR 30,000 to 60,000 excl. VAT (about USD 32,000 to 65,000). An off-the-shelf vertical tool costs EUR 18,000 to 36,000 per year in subscriptions without fitting your billing rules. Custom pays off once the firm saves 3 hours per week per engagement manager and lifts time recovery from 78 to 91%.
What the budget covers, line by line
Practice software does not replace your production ledger tools (Xero, Sage, IRIS or CCH stay in place). It is the management layer: who works on which client, for how long, at what price, and what is left to bill.
| Module | Key features | 2026 budget (EUR excl. VAT) | Timeline |
|---|---|---|---|
| Client and engagement register | Client files, engagement types, tax deadlines | 5,000 to 9,000 | 3 weeks |
| Time recording | Weekly timesheet, mobile entry, allocation per engagement | 6,000 to 12,000 | 3 to 4 weeks |
| Engagement letters | Compliant templates, e-signature, renewals | 4,000 to 8,000 | 2 to 3 weeks |
| Billing and WIP | Fixed fees, retainers, write-ups, ledger export | 7,000 to 14,000 | 4 weeks |
| Partner dashboards | Profitability per engagement, client, staff member | 4,000 to 9,000 | 2 weeks |
| Connectors | Production software API, Microsoft 365 SSO | 4,000 to 8,000 | 2 to 3 weeks |
The low end covers time and billing only. The high end adds engagement letters with e-signature and two connectors. Plan 12 to 16 weeks including user acceptance testing.
Custom vs vertical SaaS: the five-year math
| Criterion | Off-the-shelf vertical tool | Custom build |
|---|---|---|
| Upfront cost | EUR 2,000 to 5,000 setup | EUR 30,000 to 60,000 excl. VAT |
| Recurring cost (25 users) | EUR 60 to 120 per staff member per month, i.e. EUR 18,000 to 36,000 per year | Maintenance 12 to 15% of build, i.e. EUR 4,500 to 9,000 per year |
| 5-year total | EUR 92,000 to 185,000 | EUR 52,500 to 105,000 |
| Fit with your fee structures | Limited to built-in options | Complete |
| Data ownership | With the vendor | Your hosting, free export |
| Roadmap | Vendor's priorities | Yours, sprint by sprint |
Custom is not always right: below 10 staff, a vertical tool stays cheaper. Above 20, and as soon as your engagements go beyond the standard (payroll, company secretarial, advisory, one-off projects), the gap widens in favour of a dedicated build.
Measurable gains to target
| Indicator | Before (Excel) | After (2026 order of magnitude) |
|---|---|---|
| Time recovery rate | 78% | 91% |
| Reporting time per engagement manager | 3 h per week | 30 min per week |
| Up-to-date engagement letters | 65% of clients | 98% of clients |
| Delay to issue write-up invoices | 45 days | 10 days |
| Loss-making engagements spotted mid-year | Rarely | Alert at 80% of budget used |
The fastest gain comes from unbilled time: a staff member with 1,400 productive hours a year at an average EUR 85 hourly rate generates about EUR 15,000 of extra revenue when recovery improves by 13 points.
Mini case study
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Claire, partner in a 25-person accounting practice in Birmingham, has 7 engagement managers. Time saved: 7 × 2.5 h × 45 weeks = 787 hours a year, valued at EUR 85, i.e. EUR 66,900. Billing gain: 13 points on EUR 600,000 of billable volume, about EUR 78,000 recovered, of which she conservatively keeps half, EUR 39,000. Estimated annual total: EUR 105,900, for a EUR 48,000 project and EUR 7,200 annual maintenance. Payback: under six months.
FAQ
Do we need to replace our production accounting software?
No. The engagement module connects to your production tool through an API or export. That keeps the project at EUR 30,000 to 60,000 instead of EUR 150,000 or more for a full ERP.
Are generated engagement letters compliant with professional standards?
Templates are built from your approved letters and your professional body's guidance. eIDAS-grade e-signature is included at about EUR 1 per envelope.
Where is client data hosted?
With an ISO 27001-certified host in your jurisdiction, for EUR 80 to 250 per month. Backups run daily and are kept 30 days, which supports GDPR compliance.
How long until we go live?
Allow 12 to 16 weeks, including 2 weeks of scoping and 2 weeks of testing. Starting in September means going live before the January tax peak.
Can we start small?
Yes: a first time-and-billing release at EUR 18,000 to 25,000 delivered in 8 weeks, then engagement letters and dashboards in a second release.
Let's scope your project. Send us your headcount, engagement types and production tool, and we will price a scope between EUR 30,000 and 60,000 with a 12 to 16 week 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.
