The verdict in three sentences
A consultancy or IT services firm of 20 to 80 consultants in London earns more by managing utilization than by negotiating day rates. An off-the-shelf PSA (25-60 EUR/user/month) is enough while your processes fit the tool; a custom build (55,000-130,000 EUR) pays off when staffing, per-engagement margin and project billing are your core business. In both cases the enemy is not the licence price, it is the spreadsheet that hides unprofitable engagements.
What a professional services (PSA) tool covers
A PSA links sales, delivery and billing. Here are the modules and their weight in a custom build.
| Module | What it drives | Build weight (EUR) |
|---|---|---|
| Staffing & planning | Consultant allocation, utilization, capacity plan | 12,000 - 24,000 |
| Timesheet | Time entry, approval, rebilling | 8,000 - 16,000 |
| Per-engagement margin | Consultant cost vs day rate sold, live margin | 10,000 - 20,000 |
| Project billing | T&M, fixed price, milestones, credit notes | 9,000 - 18,000 |
| Sales pipeline | Opportunities, forecast, conversion | 7,000 - 14,000 |
| Executive reporting | Backlog, DSO, margin per practice | 6,000 - 14,000 |
Off-the-shelf vs custom: the real math
At 40 consultants, a market PSA at 45 EUR/user/month costs 21,600 EUR/year, or 108,000 EUR over 5 years excluding integrations. Custom becomes worthwhile when you have specifics (multiple practices, subcontracting, tiered day rates) that the standard tool charges heavily as options or forces you to work around.
| Criterion | Off-the-shelf PSA | Kolonell custom |
|---|---|---|
| Upfront cost | 3,000 - 12,000 EUR (setup) | 55,000 - 130,000 EUR |
| Recurring cost | 25 - 60 EUR/user/month | Maintenance 12 - 20 % of build/year |
| Time to go live | 6 - 12 weeks | 4 - 8 months |
| Process fit | You adapt to the tool | Tool fits your processes |
| Payroll/accounting integration | Standard connectors | Custom (Sage, Cegid, Silae) |
| Code ownership | No | Yes |
5-year TCO and utilization gain
The decisive lever: one point of utilization. On 40 consultants at 700 EUR day rate and 210 target billable days, +6 utilization points represent roughly 353,000 EUR of additional revenue per year (40 x 700 x 210 x 6 %).
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| Line | Off-the-shelf (5 yrs) | Custom (5 yrs) |
|---|---|---|
| Licences / build | 108,000 EUR | 90,000 EUR (median build) |
| Setup & integrations | 10,000 EUR | included |
| Maintenance / roadmap | 8,000 EUR | 65,000 EUR |
| Total TCO | 126,000 EUR | 155,000 EUR |
| Utilization gain (+6 pts) | partial | ~353,000 EUR/yr potential |
Mini case study
Thomas runs a 38-consultant IT services firm in London, average day rate 690 EUR. His real utilization, measured for the first time, was 74 %. After deploying a custom tool (build 82,000 EUR, maintenance 13,000 EUR/year), real-time staffing and bench alerts pushed utilization to 80 % in ten months. Revenue gain: about 38 x 690 x 205 x 6 % = 322,000 EUR/year, an investment repaid in under four months of extra margin.
FAQ
How much is a market PSA for 30 consultants? Budget 25 to 60 EUR/user/month depending on modules, i.e. 9,000 to 21,600 EUR/year, plus 3,000 to 12,000 EUR of setup in year one. Options (advanced scheduling, per-engagement margin) push the bill up fast.
When is custom justified? As soon as your specifics (subcontracting, tiered day rates, multiple practices) force you to work around the standard tool, or above 50 users where licence cost exceeds 30,000 EUR/year. The tipping point usually sits between 40 and 60 consultants.
How long to deploy? A market PSA goes live in 6 to 12 weeks; a custom build takes 4 to 8 months depending on modules and payroll/accounting integrations. We ship in stages so timesheets run by month three.
Can you integrate Silae or Cegid? Yes. Payroll (Silae) and accounting (Cegid, Sage) connectors are built to order to remove double entry and make per-engagement margin reliable. Budget 8,000 to 18,000 EUR depending on the APIs.
What ROI to expect? The first lever is utilization: +6 points on 40 consultants at 700 EUR day rate is worth about 353,000 EUR annual revenue, well above the TCO. The second is lower DSO thanks to reliable project billing.
Let's scope your project. Tell us your consultant headcount, practices and payroll/accounting tools for a staffing + billing estimate. 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.
