The verdict in three sentences
A serious online payment integration for a London SME costs between 6,000 and 18,000 GBP in 2026, depending on the number of payment methods and the level of reconciliation required. The 1.3 to 2.9 % per-transaction fees weigh more than the build itself once volume grows. The real gain is elsewhere: a failure rate cut from 10 % to 3 % and 12 hours/month of accounting reconciliation saved.
What a 2026 payment integration covers
An integration is not just a "Pay" button. It covers the payment flow, mandatory 3D Secure v2, confirmation webhooks, refunds, split payments, and reconciliation with accounting. The provider you pick (Stripe, Adyen, Mollie, PayPlug) changes the fees but not the integration effort on the site side.
| Scope | 2026 price (GBP) | Timeline | Included |
|---|---|---|---|
| Simple card payment | 6,000 - 8,000 | 3 weeks | Card, 3D Secure, webhooks |
| Card + bank transfer + wallets | 9,000 - 13,000 | 4-5 weeks | Apple/Google Pay, Open Banking |
| Split payment + B2B | 13,000 - 18,000 | 5-6 weeks | Pay in 3-4x, customer accounts, reconciliation |
| Advanced reconciliation | + 2,500 - 5,000 | + 1-2 weeks | Accounting export, auto-matching |
| Annual maintenance | 2,000 - 4,500 / yr | ongoing | API updates, monitoring |
A payment-specialised developer's day rate sits between 600 and 950 GBP in London in 2026. A senior integrator costs more but often halves the number of days on complex B2B, multi-account cases.
Fees: the real cost centre
Over time, per-transaction fees drive profitability. An SME processing 40,000 GBP/month pays between 520 and 1,160 GBP in monthly fees depending on the card/wallet mix and the share of non-UK cards.
| Provider | UK card fee | Fixed fee / transaction | Bank transfer |
|---|---|---|---|
| Stripe | 1.5 % | 0.20 GBP | Open Banking ~0.5 % |
| Adyen | 1.2 % + interchange | 0.10 GBP | variable |
| Mollie | 1.8 % | 0.20 GBP | fixed |
| PayPlug | 1.3 - 2.9 % | 0.20 GBP | non-standard |
| Non-UK card | + 1.0 - 1.5 % | same | - |
Negotiating rates becomes realistic above 50,000 GBP/month of volume; below that, list pricing applies. In continental Europe, an equivalent integration runs 6,000 to 18,000 EUR, with comparable fees but a bank-transfer ecosystem that varies by country.
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Mini case study
Marc, e-commerce director of an industrial-supplies wholesaler in London, processes 55,000 GBP/month with a legacy module showing a 10 % payment failure rate. He invests 11,000 GBP in a card + bank transfer + B2B split-payment integration, plus 3,000 GBP for reconciliation. The failure rate drops to 3 %: 7 % of 55,000 = 3,850 GBP in orders saved every month, roughly 46,000 GBP/year recovered. Automated reconciliation frees his accountant of 12 hours/month (about 300 GBP of cost). The project pays back in under three months.
FAQ
How long for a standard integration? Budget 3 to 4 weeks for a card payment with 3D Secure and tested webhooks. B2B cases (customer accounts, deferred payment) reach 5-6 weeks.
Can I keep several payment methods? Yes, and it's recommended: adding Apple Pay and Open Banking transfers lifts conversion by 5 to 12 % depending on average order value and customer base.
Does 3D Secure hurt conversion? The v2 (frictionless) version allows payment without a challenge in 60 to 80 % of eligible cases, limiting abandonment while staying PSD2 compliant.
What maintenance budget should I plan? Between 2,000 and 4,500 GBP/year for API updates, webhook monitoring, and security fixes. That is non-negotiable for payments.
Are the fees negotiable? Above roughly 50,000 GBP/month of volume, yes. Below that, the provider's list price almost always applies.
Let's scope your project. Share your target payment methods, monthly volume, and accounting tool, and we'll price the integration and reconciliation. 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.
