The verdict in three sentences
A custom client portal in London runs in 2026 between 40,000 and 90,000 GBP for a solid MVP (document space, invoices, tickets, SSO), delivered in 3 to 5 months. The real lever is not the build price but the three-year total cost, maintenance included: budget 8 to 15 % of the build per year. Scoped well, a portal cuts support calls by around 35 % and pays for itself in 12 to 18 months.
What a client portal actually costs in 2026
Price depends mostly on functional scope and how deeply it integrates with your existing systems (billing, CRM, directory). Here are the 2026 orders of magnitude seen on the London market.
| Scope | Build price (GBP) | Timeline | Maintenance / yr |
|---|---|---|---|
| MVP (docs + invoices + auth) | 40,000 - 55,000 | 3 months | 4,000 - 7,000 |
| Standard (+ tickets + SSO) | 55,000 - 70,000 | 4 months | 6,500 - 10,000 |
| Advanced (+ live billing integration) | 70,000 - 90,000 | 5 months | 9,000 - 13,000 |
| Heavy custom (multi-entity) | 90,000 - 140,000 | 6-8 months | 13,000 - 22,000 |
The day rate of a qualified team in London sits in 2026 between 600 and 950 GBP depending on seniority (dev, lead, product). An MVP therefore represents roughly 45 to 60 person-days.
The hidden line item: SSO, security and integrations
Cost overruns rarely come from the front end. They come from authentication, back-end connections and compliance.
| Item | 2026 range (GBP) | Timeline impact |
|---|---|---|
| SSO / OIDC (Azure AD, Okta) | 4,500 - 10,000 | +2 to 3 weeks |
| Billing integration (accounting API) | 6,500 - 15,000 | +3 to 5 weeks |
| Audit log + GDPR | 3,000 - 7,500 | +1 to 2 weeks |
| Managed EU/UK hosting / yr | 4,000 - 11,000 | ongoing |
| Acceptance + load testing | 4,000 - 9,000 | +2 weeks |
In Paris, at comparable scope, a client portal MVP sits in 2026 between 25,000 and 55,000 EUR — a good argument for a cost-efficient francophone partner.
Mini case study
Claire, IT director of a 120-person consulting firm in London, manages 400 active clients. Her support team handles about 90 calls/month for "resend my invoice" or "where's my file". Each call costs ~10 GBP in internal load (agent time + follow-up).
She invests 48,000 GBP in an MVP portal (docs + invoices + tickets + SSO), plus 7,000 GBP/yr in maintenance. After 3 months, calls drop 35 %, i.e. ~32 avoided calls/month = 320 GBP/month, or 3,840 GBP/yr. Adding 15 h/month of recovered admin time (valued at 30 GBP), annual savings reach ~9,200 GBP. The portal pays back in about 17 months, maintenance included.
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FAQ
How long to deliver an MVP client portal?
Expect 3 to 5 months in 2026, depending on the number of integrations. An MVP without SSO or live billing can ship in 10 to 12 weeks.
Custom build or SaaS solution?
Below 200 internal users and without specific business logic, a SaaS (from 8-15 GBP/user/month) is often enough. Beyond that, custom becomes profitable over 3 years thanks to no per-seat cost.
Is SSO essential?
For internal use, yes — it avoids password sprawl and secures access. Budget 4,500 to 10,000 GBP depending on the identity provider (Azure AD, Okta, Google Workspace).
What maintenance budget should I plan?
Between 8 and 15 % of build cost per year, i.e. 4,000 to 7,000 GBP/yr for an MVP. It covers fixes, security, version upgrades and small enhancements.
Is the portal GDPR compliant?
Yes, with EU/UK hosting, audit logging, encryption and fine-grained access control. Plan 3,000 to 7,500 GBP for this foundation if your data is sensitive.
Let's scope your project. Tell us your scope (number of users, integrations, SSO) and your indicative budget; we'll frame the most profitable MVP. 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.
