Custom client portal cost benchmark in London 2026

The verdict in three sentences

A custom client portal in London costs between 20,000 and 60,000 EUR (net) in 2026, with the dial set by authentication (SSO), role granularity and the number of integrations. A realistic timeline is 10 to 16 weeks for a first production-ready version, excluding very complex cases. Return on investment shows in a 30 to 40 % reduction in support emails and calls, not in a licence price.

What drives the price

A client portal is an authenticated space where your clients view documents, invoices, tickets and order status. The budget depends on three levers: functional scope, access security and connections to your existing systems (billing, CRM, ERP). A read-only "documents + invoices" portal is far cheaper than a transactional one with payment and workflow.

These figures are a 2026 order of magnitude for a London agency or specialised studio, excluding third-party licences (SSO, e-signature).

Total cost of ownership: beyond the build

The classic trap is to budget only the build. A portal lives on: security, version upgrades, new business requests. Plan for maintenance of 8 to 15 % of the build per year, plus hosting.

On a 40,000 EUR portal, expect 6,000 to 10,000 EUR/year of reasonable recurring cost.

Mini case study

Marc, head of operations at a B2B services SME in London (180 staff), receives 600 client emails/month for invoices, status and documents. His support team spends about 120 hours/month handling these by hand. He invests 38,000 EUR (net) in a standard portal with SSO and tickets, plus 8,000 EUR/year recurring.

After go-live, self-service absorbs 40 % of requests: 48 hours saved/month, or ~576 hours/year. At a loaded cost of 45 EUR/hour, that frees 25,900 EUR/year of time. The portal pays back in under 20 months, then yields a net recurring saving while improving client satisfaction.

FAQ

Custom portal or off-the-shelf SaaS? A SaaS (generic client portal) costs 20-80 EUR/user/month but adapts poorly to your processes. Custom pays off once you have specific workflows or more than 200 active users.

How long until production? Count 10 to 16 weeks for a useful V1, with 2 to 3 weeks of acceptance testing. A reduced MVP can ship in 6-8 weeks if scope is strictly framed.

Is SSO really necessary? If your clients already have accounts (Microsoft, Google) or security is critical, yes. SSO adds 3,000 to 8,000 EUR but cuts "forgotten password" tickets by 50 to 70 %.

How do I avoid budget overruns? Freeze a written V1 scope, a V2 backlog, and a 10-15 % contingency. 70 % of overruns come from underestimated ERP or billing integrations.

Can we start small then extend? Yes, it's recommended: a 22,000 EUR V1 that proves usage, then evolution batches. Architecture must be designed from day one to host payment and an API.

Let's scope your project. Tell us your scope (documents, invoices, tickets, integrations), user count and indicative budget. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.