Consultancy Utilisation Rate and Billing Software Cost in London (2026)

The verdict in three sentences

In a consultancy, every unrecorded hour is an unbilled hour, and an 8% leak across 35 consultants costs more than any software. In 2026 there are two routes: an off-the-shelf PSA (Professional Services Automation) such as Kantata, at roughly 20 to 45 GBP per user per month for entry tiers, or a custom tool at 26,000 to 52,000 GBP, delivered in 3 to 5 months. Custom pays off when your billing rules are unusual and your time data must feed Making Tax Digital-compatible accounting cleanly.

Where the hours and the money go

Oliver is a partner in an operations and transformation consultancy near Farringdon, 35 consultants, clients in financial services and the public sector. Time is logged on Friday in a shared spreadsheet, often from memory. Fixed-fee, time-and-materials and success-fee engagements coexist. Invoices are built by the office manager from those spreadsheets, three weeks late on average.

The finance team measured two leaks. First, about 8% of worked time is never billed: forgotten meetings, untracked overruns on fixed fees, unrecharged expenses. Second, invoicing delay inflates working capital and pushes back credit control.

The UK has no B2B e-invoicing mandate yet, but public sector buyers increasingly expect Peppol invoices and HMRC has consulted on wider adoption. A firm rebuilding its tooling now should make sure invoices can be issued in a structured format.

Off-the-shelf PSA or custom: the 2026 comparison

For a firm with standard practices, a well-chosen PSA is often enough, and Kantata is strong on resource planning for larger teams. Custom becomes relevant in three cases: mixed fee structures (fixed fee plus success fee, expenses recharged with a markup), the need for tight integration with your ERP or accounting, and the wish to use time data to steer profitability by client and engagement type.

The features that make the difference

A good tool is judged on time entry: if it takes more than two minutes a day, consultants push it to Friday and the leak returns. Priorities are mobile entry prefilled from the calendar, allocation by engagement and task, weekly approval by the engagement manager, automatic utilisation calculation, overrun alerts, then invoice generation by contract type and export to accounting.

Mini case study

Oliver's firm bills an average of 1,100 GBP per day. Its 35 consultants work about 200 days a year at 72% utilisation: 35 × 200 × 0.72 = 5,040 billable days. The 8% leak is 403 days, or 443,300 GBP of lost revenue a year.

Bringing the leak down to 3% recovers 5 points, 252 days and 277,200 GBP a year. The chosen custom tool costs 42,000 GBP plus 6,000 GBP a year. Payback takes under two months, and invoicing at day 4 instead of day 21 frees about 17 days of revenue, close to 370,000 GBP of working capital.

FAQ

Will consultants actually log their time?

Yes if entry takes under two minutes and bonuses or reviews rely on it. Firms that prefill from calendars reach 95% next-day completion.

Do we need to change accounting software?

No, the tool posts journals and invoices to Xero, Sage or your ERP. An accounting connector costs about 2,500 to 5,000 GBP.

Can we start with a PSA and move to custom later?

Yes, and it can be wise. Insist on full exports of time and invoices, otherwise migration will take 2 to 4 weeks.

How do we track profitability by engagement?

By costing every hour at the consultant's fully loaded cost, often 45 to 65% of the selling rate. A dashboard compares planned and actual margin every week.

Is Kantata overkill for 35 people?

Often partly: its strength is resource planning across hundreds of consultants. Firms under 50 people frequently use 30 to 40% of its modules, which weighs on value for money.

Let's scope your project. Share your contract types and billing chain: we compare PSA and custom on your case and propose a 3 to 5 month plan. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.