The verdict in three sentences
A custom client portal for an accounting firm with 1,800 client files costs between EUR 35,000 and 80,000 (about GBP 30,000 to 68,000) in 2026, including the connection to the practice management software. An off-the-shelf solution billed at EUR 8 to 15 per client per month adds up to EUR 172,800 to 324,000 per year for the same volume. Custom becomes rational beyond 800 to 1,000 files, provided you precisely price the 2 hours saved per file per year.
Custom or off-the-shelf: the 5-year comparison
A CIO's first reflex is to compare a development quote with a subscription. The right comparison is total cost over the portal's lifetime.
| Criterion | Off-the-shelf solution | Custom portal |
|---|---|---|
| Upfront cost | EUR 2,000 to 8,000 (configuration) | EUR 35,000 to 80,000 |
| Recurring cost (1,800 clients) | EUR 8 to 15 per client per month, i.e. EUR 172,800 to 324,000 per year | Hosting and maintenance EUR 8,000 to 15,000 per year |
| Total cost over 5 years | EUR 866,000 to 1,628,000 | EUR 75,000 to 155,000 |
| Journey customization | Limited to available options | Full, in the firm's branding |
| Practice software connection | Standard connectors only | Custom, EUR 6,000 to 15,000 |
| Data ownership | With the vendor | Controlled hosting, in-country |
| Time to go live | 2 to 6 weeks | 14 to 22 weeks |
Note: vendor pricing is often tiered, and a firm with 1,800 files frequently negotiates EUR 4 to 6 per client. Even at EUR 5, the annual cost reaches EUR 108,000, which keeps custom ahead from year two.
Features and their cost
| Module | Indicative 2026 cost (excl. VAT) | Expected gain |
|---|---|---|
| Document upload (drag and drop, mobile photo) | EUR 8,000 to 15,000 | No more email chasing |
| OCR and automatic filing | EUR 5,000 to 12,000 | 30 to 40% less data entry |
| Tax and payroll deadline calendar | EUR 4,000 to 8,000 | Fewer missed VAT and filing deadlines |
| Secure messaging and e-signature | EUR 5,000 to 10,000 | Engagement letters signed in 48 h |
| Practice software connection | EUR 6,000 to 15,000 | Documents land directly in the file |
| Strong authentication and access log | EUR 3,000 to 6,000 | GDPR and confidentiality compliance |
| Staff dashboard | EUR 4,000 to 14,000 | Visibility on missing documents |
The minimum viable core (document upload, deadlines, practice software connection and security) sits around EUR 35,000. The full version with OCR and e-signature exceeds EUR 70,000.
Mini case study
Oliver, CIO of a 60-person accounting firm in London, manages 1,800 client files. He picks a custom portal at EUR 58,000 (about GBP 49,500), with EUR 11,000 per year for hosting and maintenance.
The gain measured during the pilot is 2 hours per file per year: fewer reminders, less re-keying, fewer calls. Across 1,800 files, that is 3,600 hours. Valued at a fully loaded staff cost of EUR 45 per hour, the gain reaches EUR 162,000 per year. The portal pays for itself in just over 4 months of full use. In practice, with gradual adoption by 60% of clients in year one, payback comes in 7 to 8 months.
Adoption: the factor that makes or breaks the project
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A portal clients do not use earns nothing. Firms that reach 80% adoption within 12 months apply three rules: upload works from a smartphone in under 30 seconds, every staff member demos the portal at the year-end review meeting, and documents sent by email are gradually refused from month six.
FAQ
From how many files is custom profitable?
Below 500 files, an off-the-shelf solution remains cheaper. Between 800 and 1,000 files, custom pays off in 2 to 3 years, and above 1,500 files from year two.
Where are client documents hosted?
We recommend in-country hosting, ISO 27001 certified depending on sensitivity, for EUR 300 to 900 per month. Documents are encrypted at rest and every access is logged to meet professional confidentiality requirements.
Does the portal connect to our practice software?
Yes, via API when the vendor offers one, or through scheduled file exchange otherwise. This item costs EUR 6,000 to 15,000 depending on the software and sync level required.
How long until go-live?
Allow 14 to 22 weeks, including a 3 to 4 week pilot with 50 to 100 volunteer clients. Rollout to all files then happens in waves of 300.
Can we start with document upload only?
Yes, a first phase of EUR 25,000 to 35,000 covers upload, security and the practice software connection. OCR and e-signature modules are added later without a rebuild.
Let's scope your project. Share your number of client files, your practice software and your priority modules: we will price the portal, its hosting and the rollout 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.
