The verdict in three sentences
For a firm serving 400 small-business clients, a custom client portal costs between EUR 25,000 and 55,000 excl. VAT (about GBP 21,500 to 47,000) and becomes cheaper than a SaaS subscription after roughly 26 months. SaaS remains the right choice below 150 clients or if your processes match the off-the-shelf tool. Above that, control over the document collection journey, UK or EU data hosting and integration with your practice software justify the investment.
What document chasing costs you today
In a typical mid-sized firm, an accountant spends about 6 hours a week chasing bank statements, purchase invoices and expense receipts by email and phone. Over 46 working weeks, that is 276 hours a year. At the loaded cost of an experienced accountant (around EUR 45 an hour in 2026, higher in central London), the direct loss reaches EUR 12,400 a year, before counting late accounts and filing penalties.
| Item | Today | With a client portal | Annual difference |
|---|---|---|---|
| Chasing hours per week | 6 h | 1.5 h | -207 h |
| Cost of chasing (EUR 45/h) | EUR 12,400 | EUR 3,100 | -EUR 9,300 |
| Average time to receive documents | 19 days | 8 days | -11 days |
| Accounts filed late | 7% | 2% | -5 points |
| Untracked email exchanges | 70% | 10% | -60 points |
| Time to sign an engagement letter | 9 days | 2 days | -7 days |
These are 2026 orders of magnitude observed in firms of 8 to 15 staff. They help size the budget; they are not a guarantee.
Custom build or SaaS: the costed comparison
Market SaaS portals usually charge EUR 8 to 15 per client per month depending on modules (document upload, e-signature, messaging, dashboard). For 400 clients, the bill climbs fast.
| Criterion | Market SaaS portal | Custom portal |
|---|---|---|
| Upfront investment | EUR 0 to 3,000 setup | EUR 25,000 to 55,000 excl. VAT |
| Recurring cost (400 clients) | EUR 38,400 to 72,000 a year | EUR 4,000 to 8,000 a year (hosting + maintenance) |
| Cumulative 3-year cost | EUR 115,000 to 216,000 | EUR 37,000 to 79,000 |
| Hosting | Often outside your jurisdiction | UK or EU, ISO 27001 provider of your choice |
| Practice software integration | Standard connectors | Custom API (Xero, Sage, IRIS, CCH) |
| Client journey customisation | Limited to options | Full, under your brand |
| Time to go live | 2 to 4 weeks | 3 to 4 months |
The break-even calculation is simple: with a EUR 40,000 project and EUR 6,000 of annual running costs, against SaaS negotiated at EUR 8 per client (EUR 38,400 a year), the monthly gap is about EUR 2,700. But most firms start on an entry-level SaaS at EUR 4 or 5 per client before moving up. On a weighted average of our projects, break-even lands around 26 months.
Functional scope and price
| Module | Function | Indicative budget excl. VAT |
|---|---|---|
| Secure client area | Two-factor authentication, multiple users per client file | EUR 5,000 to 9,000 |
| Document upload | Drag and drop, mobile photo, OCR, automatic filing | EUR 6,000 to 14,000 |
| E-signature | Engagement letters, accounts approval, DocuSign integration | EUR 3,000 to 6,000 |
| Messaging and reminders | Thread per client, scheduled automatic reminders | EUR 4,000 to 8,000 |
| Client dashboard | Revenue, cash position, tax deadlines | EUR 5,000 to 12,000 |
| Practice software connector | Sync of documents and entries | EUR 2,000 to 6,000 |
A first EUR 25,000 phase covers the secure area, document upload and reminders. E-signature and the dashboard can follow in phase 2, funded by phase 1 savings.
Mini case study
Claire, partner at a 12-person accounting firm in London, manages 410 small-business clients. Her current SaaS costs EUR 11 per client per month, or EUR 54,120 a year. She commissions a custom portal at EUR 42,000 excl. VAT, hosted in the UK, with EUR 6,500 of annual maintenance.
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- Annual subscription saving: 54,120 - 6,500 = EUR 47,620
- Chasing time saved: 207 h x EUR 45 = EUR 9,300
- Total first-year gain: about EUR 56,900, a payback under 10 months in her specific case
With a cheaper SaaS at EUR 6 per client, break-even would move to about 20 months. That is the calculation we run with every firm before quoting.
FAQ
How long does it take to launch a client portal?
Allow 3 to 4 months for a complete first phase, including 3 weeks of scoping and 2 weeks of acceptance testing with a panel of 20 pilot clients. Migrating existing client files takes 1 to 2 additional weeks.
Is the portal GDPR compliant and confidential?
Yes, local hosting, encryption of documents at rest and two-factor authentication are included from phase 1. Access logs are kept for 12 months to meet professional body requirements.
Will my small-business clients actually use it?
Mobile photo upload is the key: in equipped firms, 65 to 80% of clients upload documents without reminders after 6 months. An SMS onboarding campaign and a 90-second video are usually enough.
Can the portal connect to our practice software?
Yes, through the Xero, Sage, IRIS or CCH APIs, for EUR 2,000 to 6,000 excl. VAT. Uploaded documents land directly in the right company and financial year.
What if we want to change provider later?
You own the source code and the database, and the contract says so. Technical documentation is delivered so another team can take over in under 4 weeks.
Let's scope your project. Send us your client count, practice software and current subscription: we will price a first phase between EUR 25,000 and 55,000 excl. VAT, delivered in 3 to 4 months. 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.
