The verdict in three sentences
An accounting firm managing 900 engagement letters in Word spends the equivalent of three working weeks a year on drafting, chasing signatures and compliance checks. A custom module at EUR 15,000 to 28,000 excluding VAT (about GBP 13,000 to 24,000), delivered in 8 weeks, generates letters that follow professional body requirements, gets them e-signed and feeds fee billing directly. The return comes less from the 120 hours saved than from out-of-scope fees finally being billed.
Why Word no longer works in 2026
Professional bodies such as the ICAEW and ACCA expect every client engagement to be covered by a signed letter that defines the scope precisely, and practice assurance reviews check it. In Word, each team member copies a template, edits clauses, prints, scans and files. With 900 clients, gaps are inevitable: outdated template versions, letters not refreshed after a change of tax status, one-off assignments done without an addendum.
| Process step | In Word (per letter) | With custom module | Annual gain on 900 letters |
|---|---|---|---|
| Drafting and clause selection | 25 min | 4 min | 315 h in theory |
| Partner compliance review | 8 min | 2 min | 90 h |
| Sending, signing, reminders | 12 min | 1 min | 165 h |
| Archiving and filing | 5 min | 0 min | 75 h |
| Entering fees into billing | 6 min | 0 min | 90 h |
| Annual renewal | 10 min | 1 min | 135 h |
Theoretical gains exceed 800 hours, but the cautious estimate most firms use is 120 net hours actually recovered in year one, while teams adopt the tool. That 2026 order of magnitude is what belongs in a business case.
What a custom module includes and what it costs
The typical scope links three components: a letter generator built on a library of approved clauses, an eIDAS and UK-compliant e-signature flow, and a bridge to your practice management or billing software.
| Component | 2026 range excl. VAT | Timeline | Note |
|---|---|---|---|
| Clause library and templates per service | EUR 3,500 to 6,000 | 2 weeks | Bookkeeping, payroll, company secretarial, advisory |
| Rules-based generator (tax status, entity type, turnover) | EUR 4,000 to 7,000 | 2 weeks | Automatic clause selection |
| E-signature (Yousign or Docusign API) | EUR 2,000 to 3,500 | 1 week | About EUR 0.80 to 1.50 per signature |
| Fee billing link | EUR 3,000 to 6,500 | 2 weeks | Fixed fees, time-based fees, addenda |
| Renewal dashboard and alerts | EUR 1,500 to 3,000 | 1 week | Expired letters, work without addendum |
| Testing, data migration, training | EUR 1,000 to 2,000 | 0 to 1 week | Import of 900 existing clients |
| Total | EUR 15,000 to 28,000 | 8 weeks | Maintenance EUR 150 to 400 per month |
The low end fits a firm that keeps its current practice software and only needs an export to billing. The high end includes two-way sync with practice software, automatic addenda and a client portal where directors view their signed letters.
Custom or off-the-shelf?
Practice management suites often include an engagement letter module. It works if your services are standardised. Custom becomes relevant when the firm has built an advisory offer, tiered fixed fees or complex payroll assignments that a generic template cannot describe.
| Criterion | Module built into practice software | Custom module |
|---|---|---|
| Upfront cost | EUR 0 to 3,000 | EUR 15,000 to 28,000 excl. VAT |
| Annual cost | EUR 15 to 40 per user per month | EUR 1,800 to 4,800 maintenance |
| 5-year cost (35 staff) | EUR 31,500 to 84,000 | EUR 24,000 to 52,000 |
| Custom clauses per service type | Limited | Unlimited |
| Link to evolving fixed-fee billing | Partial | Full |
| Ownership of code and data | Vendor | Firm |
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Claire, partner at a 35-person firm in the City of London, manages 900 engagement letters. She invests EUR 22,000 excluding VAT in a custom module. The 120 hours saved, valued at EUR 65 loaded hourly cost, represent EUR 7,800 a year. More importantly, the dashboard reveals 60 clients receiving one-off work (interim accounts, funding applications) without an addendum: at an average EUR 250 billed, that is EUR 15,000 in recovered fees. Total gain reaches EUR 22,800 in year one, a payback in under 12 months, including EUR 2,400 of maintenance.
FAQ
Does a custom module meet professional body review requirements?
Yes, provided the clause library is approved by a partner and version-controlled. Each letter keeps the template version used, the signature date and the exact scope, which simplifies practice assurance visits.
How much does e-signature cost in use?
Budget EUR 0.80 to 1.50 per signed envelope depending on volume. For 900 letters a year, the cost stays under EUR 1,400 annually.
Can existing Word letters be migrated?
Client data (entity type, tax status, fees) is imported from a practice software export. Old signed letters are archived as PDFs and attached to each client file, with no re-keying.
How much lead time before the renewal campaign?
The module ships in 8 weeks. For a January renewal campaign, start the project in early October at the latest.
Do we need to change practice software?
No. The module connects via API or scheduled export to the main tools on the market, and the firm keeps its current environment.
Let's scope your project. Send us your letter volume, service types and billing tool and we will price a scope between EUR 15,000 and 28,000 excluding VAT with an 8-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.
