The verdict in three sentences
A B2B online payment integration for a London SME costs between 6,000 and 20,000 EUR depending on payment methods, reconciliation and ERP wiring. Transaction fees (card ~1.4% + 0.25 EUR, bank transfer near-free) matter less than the DSO cost you eliminate. Budget 3 to 6 weeks of delivery and a 300-700 EUR/month maintenance fee for a reliable, PCI-DSS compliant setup.
What integration costs in 2026
The budget hinges on scope: a simple payment link, or a customer portal wired to billing with automated reconciliation.
| Scope | 2026 cost (EUR) | Delay | Included |
|---|---|---|---|
| Payment link + card | 6,000 - 9,000 | 3 weeks | Stripe/Mollie, hosted page, webhook |
| Customer portal + transfer | 10,000 - 14,000 | 4-5 weeks | Invoice space, transfers, reminders |
| + ERP reconciliation | 15,000 - 20,000 | 6 weeks | Auto-matching, accounting map, exports |
| Multi-entity / multi-currency | 20,000 - 28,000 | 7-8 weeks | Consolidation, EUR/USD/GBP, audit |
2026 ballpark estimate for a quality vendor, excluding third-party SaaS subscriptions.
Transaction fees: what you really pay
In B2B the payment-method mix matters more than the headline rate: steering toward bank transfer melts the bill.
| Method | 2026 fee (ballpark) | Settlement | B2B use |
|---|---|---|---|
| Card (EU) | ~1.4% + 0.25 EUR | D+1 to D+2 | Small amounts, urgency |
| Card (non-EU) | 2.5-2.9% + 0.25 EUR | D+2 | International clients |
| Bank transfer (SEPA) | 0 - 0.35 EUR fixed | D+1 | Large, recurring |
| Direct debit | ~0.35% (capped) | D+2 to D+3 | Subscriptions, schedules |
| Wallet (Apple/Google Pay) | ~1.4% + 0.25 EUR | D+1 | Mobile, fast checkout |
On a 3,000 EUR invoice, card costs ~42.25 EUR; transfer costs ~0.35 EUR. Routing 70% of volume to transfer cuts the fee bill by more than three.
Security and compliance
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The PCI-DSS standard is carried by the payment provider (Stripe, Mollie, Adyen) via a hosted page or tokenised fields: you never store the card number. 3-D Secure 2 (SCA) is mandatory on EU cards and lowers the failure rate when tuned well (low-value and recurring exemptions). A poorly managed failure rate is costly: 2-4% of lost payments become manual chasing.
Mini case study
Claire, CFO of a 45-person industrial SME in London, invoices 180 business clients with an average 52-day DSO. She rolls out a customer portal with card + transfer for 13,500 EUR, maintenance 450 EUR/month. Six months later DSO drops to 34 days: on 6.2 M EUR revenue, those 18 days free roughly 306,000 EUR of one-off working capital and, at overdraft cost (~6%), save ~18,000 EUR/year in financial charges. Annual payment fees: ~9,500 EUR (transfer-heavy mix). The setup pays for itself in under 5 months.
FAQ
What does the minimal integration cost? A reliable card payment link, with confirmation webhook and basic matching, ships for 6,000-9,000 EUR in about 3 weeks.
What per-transaction fees in 2026? Expect ~1.4% + 0.25 EUR on EU cards, 2.5-2.9% off-EU, and near-zero on bank transfer. The mix drives 80% of your fee bill.
How long to go live? Between 3 and 6 weeks by scope: simple link 3 weeks, portal with ERP reconciliation 6 weeks.
Must I be PCI-DSS compliant myself? No if you use a hosted page or tokenised fields: the provider carries most compliance (SAQ-A). You avoid storing card data.
What real gain to expect? The true value is lower DSO: moving from 50 to 35 days often frees tens of thousands in cash, far beyond the fees.
Let's scope your project. Tell us your invoice volume, target payment methods and ERP: we'll price the integration, fees and maintenance. 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.
