The verdict in three sentences
A client portal for a service SME costs EUR 25,000 to 70,000 (about GBP 21,000 to 60,000) in 2026, with go-live in 8 to 14 weeks. Return on investment comes mainly from a 30 to 50% drop in calls and email chasers about case progress and invoices. Strong authentication and regional hosting (EUR 100 to 400 a month) are not options: they are what makes B2B clients willing to upload their documents. London agencies typically quote 15 to 30% above these ranges.
Three portal levels and their price
Budget depends on the feature set and above all on connections to your existing tools (ERP, invoicing software, document management). A standalone portal where staff re-enter data by hand is cheaper to build, but far more expensive to run.
| Level | Key features | 2026 budget (EUR, excl. VAT) | Timeline | Monthly hosting |
|---|---|---|---|---|
| Essential | Secure login, case tracking, document upload | 25,000 to 35,000 | 8 to 10 weeks | EUR 100 to 150 |
| Integrated | + synced invoices, online payment, notifications | 35,000 to 50,000 | 10 to 12 weeks | EUR 150 to 250 |
| Advanced | + e-signature, messaging, multi-site, ERP API | 50,000 to 70,000 | 12 to 14 weeks | EUR 250 to 400 |
| Mobile app option | Installable PWA, push notifications | + 6,000 to 12,000 | + 3 weeks | included |
| Multilingual option | EN, FR, DE | + 3,000 to 6,000 | + 1 to 2 weeks | included |
| Ongoing maintenance | Fixes, updates, small changes | 15 to 20% of build cost per year | ongoing | separate |
For an industrial or professional services SME, the Integrated level is the most common: it removes double entry and pays back in under two years.
Security and compliance: what belongs in the specification
Clients will upload contracts, purchase orders and personal data. The portal must meet UK GDPR and the expectations of large-account procurement teams, which increasingly send security questionnaires before signing.
| Requirement | Recommended implementation | Indicative extra cost (EUR) | Why |
|---|---|---|---|
| Strong authentication | MFA via app or email, Microsoft SSO for large accounts | 2,000 to 5,000 | Required by 70% of procurement questionnaires |
| Regional hosting | AWS London, Azure UK South or EU region | included in hosting | Sensitive data, sovereignty |
| Document encryption | At rest and in transit, signed links | 1,000 to 2,500 | Prevents contract leaks |
| Audit log | Access and download history | 1,500 to 3,000 | Traceability in disputes |
| Granular permissions | Roles by client, site, user | 2,000 to 4,000 | Several contacts per account |
| Pre-launch penetration test | External audit | 3,000 to 7,000 | Meets large-account demands |
Measurable customer service gains
ROI is calculated on three levers: calls avoided, accounts receivable chasing time, and faster payment when invoices can be viewed and paid online.
| Metric | Before portal | After 6 months | Change |
|---|---|---|---|
| Status calls per month | 600 | 330 to 420 | 30 to 45% fewer |
| Document request emails | 400 | 150 to 200 | 50 to 60% fewer |
| Average days to pay | 52 days | 40 to 45 days | 7 to 12 days faster |
| Time to handle a request | 12 min | 4 min | 8 min saved |
| Customer satisfaction (NPS) | +18 | +30 to +40 | stronger retention |
Mini case study
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Oliver, operations director of an industrial maintenance SME in London (120 clients, 45 staff), receives 600 status calls a month averaging 6 minutes. With an Integrated portal at EUR 42,000, calls fall by 40%, i.e. 240 calls avoided and 24 hours freed every month. At a loaded hourly cost of EUR 38, that is about EUR 11,000 a year, plus 9 days faster payment on EUR 4 million of revenue, freeing nearly EUR 100,000 of cash. The portal pays back in under three years on time savings alone, and immediately once cash flow is counted.
FAQ
What is the minimum budget for a serious client portal?
Budget EUR 25,000 for secure login, case tracking and document upload. Below that you get a file-sharing space rather than a real portal.
Why not use an off-the-shelf SaaS portal?
A SaaS portal costs EUR 15 to 40 per user per month, i.e. EUR 18,000 to 48,000 a year for 100 users. Custom becomes cheaper from year three and fits your processes.
How long to connect our ERP?
Connecting Sage, Xero, NetSuite or Odoo takes 2 to 4 weeks and costs EUR 4,000 to 10,000 depending on the API.
Will clients actually use it?
Adoption reaches 60 to 80% within six months if invoices and documents are only available on the portal. A 2 to 3 week launch programme is recommended.
What is the yearly cost after launch?
Plan 15 to 20% of build cost for maintenance, plus EUR 1,200 to 4,800 of hosting per year.
Let's scope your project. Tell us about your cases, invoicing tools and number of active clients: we quote your portal between EUR 25,000 and 70,000, deliverable in 8 to 14 weeks. 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.
