The verdict in three sentences
A custom B2B client portal costs between 35,000 and 90,000 EUR in 2026, plus roughly 20 % if you add SSO and connected billing. The real question is not price but ROI: self-service portals cut support calls by 40 % and payment delays by 25 %. Custom is justified as soon as your ordering process falls outside an ERP module's standard.
What a client portal costs in 2026
| Scope | Key features | 2026 budget (EUR) | Timeline |
|---|---|---|---|
| Standard portal | Orders, invoices, tickets | 35,000 – 55,000 | 3 – 4 months |
| Advanced portal | + SSO, online payment, custom catalog | 55,000 – 90,000 | 4 – 6 months |
| Premium portal | + ERP-connected billing, multi-entity | 90,000 – 140,000 | 6 – 8 months |
Recurring costs: hosting 200 to 800 EUR/month by traffic, maintenance 12 to 15 %/year of build. SSO (single sign-on) and real-time billing add about 20 % to the initial project.
The ROI calculation that convinces management
A well-designed portal shifts load from support to self-service. 2026 order of magnitude for a base of 400 active customers:
| Item | Before portal | After portal | Gain |
|---|---|---|---|
| Support calls/emails per month | 900 | 540 | -40 % |
| Average payment delay | 52 days | 39 days | -25 % |
| Billing admin time per week | 22 h | 9 h | -59 % |
| Order errors per month | 35 | 12 | -66 % |
On this basis, annual savings (support time + cash flow + errors) often exceed 60,000 to 90,000 EUR, an 8 to 14 month payback.
Custom build or an existing ERP module?
| Criterion | Custom portal | ERP portal module |
|---|---|---|
| Initial cost | 35,000 – 90,000 EUR | 8,000 – 25,000 EUR setup |
| Recurring cost | Maintenance 12-15 %/year | Per-user license |
| Customer experience | Tailored, strong brand | Standard, often dated |
| Process flexibility | Total | Limited to vendor model |
| Code ownership | You | Vendor |
The ERP module wins on entry cost; custom wins as soon as customer experience and process specificity become differentiators.
Mini case study
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Claire, sales director of a medical equipment distributor in Lyon (600 professional customers), launches a portal at 68,000 EUR with SSO and real-time order tracking. After 12 months: support calls down from 780 to 470 per month (-40 %), payment delay from 55 to 41 days. The cash-flow gain on 1.2 M EUR of receivables is roughly 18,000 EUR of avoided interest and fees, plus 1.3 FTE of support reallocated. ROI reached in 11 months.
FAQ
What is the minimum budget for a credible client portal?
From 35,000 EUR for orders, invoices and tickets. Below that you get a simple download area, not real self-service.
Is SSO really necessary?
It becomes essential once your customers already have accounts elsewhere (ERP, extranet). SSO adds ~20 % but removes login friction, the main barrier to adoption.
How long before I see ROI?
Usually 8 to 14 months, driven by fewer support calls and faster payments. The threshold depends mostly on your active customer volume.
Can the portal connect to our ERP?
Yes, via API or connector. Real-time connected billing is the most expensive item but also the most profitable on the cash-flow side.
How do we guarantee customer adoption?
Guided onboarding, email nudges and self-service on the most frequent tasks (invoices, order status) push adoption above 70 % within 3 months.
Let's scope your project. Tell us your active customer count and priority features (orders, invoices, SSO) and we will quote the portal and its expected ROI. 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.
