The verdict in three sentences
A custom client portal for an accounting practice costs between EUR 18,000 and 45,000 (ex. VAT) in 2026, depending on scope (document management, e-signature, notifications, integration to your production software). It saves the team 6 to 10 hours per week by removing email back-and-forth and missing documents. The real calculation isn't the build price but the cost of the administrative time you already pay for every month.
What each portal tier covers
An accounting portal isn't just a file drop box: it's a structured flow between the client, the fee earner and the production tool. Here are the common tiers seen in the London market in 2026.
| Tier | Indicative price 2026 (ex. VAT) | Key features | Timeline |
|---|---|---|---|
| Essential | EUR 18,000 – 24,000 | Shared document management, secure upload, email notifications, authentication | 3 months |
| Professional | EUR 25,000 – 35,000 | + e-signature, automated reminders, deadline dashboard | 4 months |
| Advanced | EUR 36,000 – 45,000 | + production tool integration, payroll portal, custom reporting | 5 months |
On top of these figures, budget maintenance of 12 to 18 % of the project cost per year, roughly EUR 3,000 to 8,000/year covering hosting, security, updates and support.
Custom build or existing SaaS?
Accounting SaaS products already offer a client area. The real question is the degree of integration with YOUR process and production tool (permanent file, accounts prep, review).
| Criterion | Existing SaaS | Custom portal |
|---|---|---|
| Upfront cost | EUR 15 – 60/user/month | EUR 18,000 – 45,000 once |
| 4-year cost (12 staff) | ~EUR 35,000 – 45,000 | ~EUR 30,000 – 60,000 (build + maintenance) |
| Production tool integration | Limited / generic connectors | Bespoke, exact workflow |
| Brand customisation | Low | Full (white label) |
| Data hosting | With the vendor | Where you decide (EU) |
| Vendor lock-in | High | None |
Below 8 staff, a SaaS is often enough. Beyond that, or if integration with production is strategic, custom becomes cost-effective and avoids vendor dependency.
Mini case study
Claire is a partner at a 14-strong accounting practice in central London. Her teams spend on average 8 hours per week chasing clients for missing documents and filing items received by email. Estimated loaded cost: EUR 32/hour, i.e. 8 × 32 × 47 weeks ≈ EUR 12,000/year of administrative time.
She invests EUR 31,000 in a Professional portal with automated reminders and e-signature. By month 4, chasing time drops to 2 h/week. Annual saving: ~EUR 9,000 of recovered time, plus signed accounts in 2 days instead of 3 weeks. The build pays for itself in about 3.5 years, before even counting new clients won thanks to the premium image.
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FAQ
How long to deliver an accounting portal?
Count 3 to 5 months depending on the tier. The Essential tier ships in 3 months; production tool integration adds 1 to 2 months of development and testing.
Is the e-signature compliant?
Yes, an advanced or qualified (eIDAS) e-signature can be integrated. Budget EUR 1 to 3 per signature depending on volume and the chosen provider.
Can the portal connect to our accounting production software?
Yes, via API or a dedicated connector. It's the heaviest line in the quote (EUR 5,000 to 12,000) but also the one that generates the most time savings.
What annual maintenance budget should we plan?
Between 12 and 18 % of the project cost per year, i.e. EUR 3,000 to 8,000/year. It covers EU hosting, security, updates and user support.
Is the portal mobile-friendly?
Yes, it's built responsive or as a PWA. Your clients upload an invoice or sign accounts from their phone, which noticeably speeds up exchanges.
Let's scope your project. Tell us about your production tool, headcount and the workflows to digitise, and we'll frame a scope to a realistic budget. 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.
