A merchant account is a specialist bank account that sits between your customer’s card payment and your business bank account, temporarily holding funds while the card networks verify and settle the transaction. A payment gateway is the software layer that routes transaction data from your website or card terminal through to those card networks. The confusion arises because, for most small UK businesses, you no longer need to think about either separately. Payment Service Providers (PSPs) like Square, SumUp, and PayPal POS bundle both into a single product – you sign up, get a card reader, and start taking payments within hours.
Where you do need to understand the distinction is when your card turnover crosses roughly £50,000 per year, when you operate in multiple countries, or when you process in a regulated or high-risk sector. At that point, a traditional merchant account with Interchange++ pricing can save thousands annually – but it comes with an application process, underwriting, and a contract.
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This guide explains how a merchant account and a payment gateway each work, where PSPs fit in, and how to work out which setup is right for your business at your current stage.
- A merchant account is a dedicated financial relationship with an acquiring bank - you are underwritten individually, which means an application process but better rates at £50,000+ monthly volume
- A payment gateway is software that routes card data between your website and the payment processor - Stripe, PayPal, and Braintree are gateways, while Worldpay and Barclaycard are traditional acquirers
- Combined providers like Square and SumUp bundle both into one product with no application process - instant setup and flat-rate pricing (1.69-1.75%) but no room to negotiate rates as volume grows
- Separate merchant accounts become cost-effective above £50,000/month in card turnover - interchange++ pricing can reduce effective rates to 0.5-1.0%, saving hundreds per month versus flat-rate
- Most UK SMEs should start with a combined provider and only separate when turnover justifies it - the admin overhead of managing a separate merchant account and gateway is not worth it under £20,000/month
What Is a Merchant Account?
A merchant account is a specialist bank account that temporarily holds card payment funds during the settlement process before releasing them to your business bank account, typically within 1-3 working days.
When a customer pays by card, the money doesn’t flow directly into your current account. It passes through a merchant account first – a dedicated account issued by an acquiring bank (also called an acquirer). The acquirer underwrites your business, accepts the financial risk of chargebacks on your behalf, and manages the settlement of funds from the card networks (Visa, Mastercard) into your account.
Traditional merchant accounts are issued by specialist acquirers or banks. In the UK, the major providers include:
- Worldpay – the UK’s largest acquirer, used by over 400,000 businesses
- Barclays / Barclaycard Payments – bank-issued merchant accounts with strong brand recognition
- Lloyds Cardnet – the acquiring arm of Lloyds Banking Group
- takepayments – a reseller/acquirer focused on SMBs with tailored pricing
- Elavon – US Bank subsidiary, popular with larger UK retailers and hospitality groups
Applying for a merchant account involves underwriting. The acquirer assesses your business type, expected monthly turnover, average transaction value, and chargeback risk before issuing an account. You’ll typically need: a VAT number or UTR, business bank account details, 3-6 months of trading history (sometimes waived for startups), and in some cases, a credit check.
Settlement timing with a traditional merchant account is usually T+1 to T+3 (1-3 working days after the transaction). Some acquirers offer faster settlement for a fee.
What Is a Payment Gateway?
A payment gateway is software that encrypts and routes card transaction data between your website or terminal and the card networks, authorising or declining payments in real time.
A payment gateway handles the technical routing of a card transaction. When a customer enters their card details on your website or taps their card on a terminal, the gateway encrypts that data, sends it to the relevant card network (Visa, Mastercard), receives the authorisation response, and passes the result back to your checkout or terminal – all in under two seconds.
Crucially, a payment gateway does not hold or process funds. It only handles the data flow. The actual movement of money is handled by the merchant account (acquirer) sitting behind it.
Payment gateways come in two main forms:
- Hosted gateways – redirect customers to the provider’s own payment page (e.g. PayPal Checkout). Easiest to integrate, but the customer leaves your site.
- Integrated gateways – process payments within your own website via API (e.g. Stripe, Adyen). Full control over the customer experience, but requires developer effort.
Well-known UK payment gateway providers include:
- Stripe – developer-focused API-based gateway, online-only, widely used for e-commerce and SaaS
- PayPal Checkout – hosted gateway, popular for consumer-facing e-commerce
- Opayo (formerly Sage Pay) – UK-focused gateway used by mid-market retailers
- Adyen – enterprise-grade gateway that also includes its own acquiring (so functions as both gateway and merchant account)
- Worldpay Gateway – Worldpay’s own online gateway, often bundled with its merchant account
A standalone gateway like Stripe requires you to connect it to a merchant account. Stripe itself can act as the acquirer (via its own banking licences) or connect to your own acquirer if you have one. This is where the terminology gets blurry.
A payment gateway is infrastructure, not a financial relationship. It handles data, not money. You can think of it as the pipeline; the merchant account is the bank at the end of the pipeline. For in-person payments via a card terminal, the “gateway” function is handled by the terminal hardware itself – you only hear the term “gateway” separately when selling online.
Merchant Account vs Payment Gateway: Key Differences
A merchant account holds and settles card funds via an acquiring bank; a payment gateway routes transaction data to the card networks. One moves money, the other moves data – but most businesses use a PSP that combines both.
| Feature | Merchant Account | Payment Gateway |
|---|---|---|
| What it does | Holds and settles card funds during processing | Routes transaction data between checkout and card networks |
| What type of product | Financial account (issued by acquirer/bank) | Software / API |
| Setup process | Application, underwriting, credit check | API key or hosted integration – instant |
| Cost structure | Monthly fee + per-transaction fee (IC++ or blended) | Monthly fee (sometimes) + per-transaction fee |
| Who carries risk | Acquirer carries chargeback and fraud risk | Gateway has no financial exposure |
| Settlement | Acquirer settles funds to your bank (T+1 to T+3) | No settlement function – data only |
| Contract | Often 12-36 months with traditional acquirers | Usually month-to-month or PAYG |
| Who needs it separately | Businesses processing >£50K/year, high-risk sectors | Businesses with their own acquiring, needing online checkout |
| Examples (UK) | Worldpay, Barclaycard, takepayments, Elavon | Stripe, Opayo, PayPal Checkout, Adyen Gateway |
The short version: you need both to process card payments, but you don’t always need to source them separately. That’s where Payment Service Providers come in.
What Is a Payment Service Provider (PSP)?
A Payment Service Provider bundles a merchant account and payment gateway into a single product under their master acquiring licence – meaning you can start accepting card payments in minutes with no separate application or underwriting.
A PSP operates under its own FCA-regulated e-money or payment institution licence and holds a master merchant account with an acquiring bank. When you sign up with Square, SumUp, or PayPal POS, you’re not getting your own dedicated merchant account – you’re processed as a sub-merchant under their umbrella. This is called aggregated processing.
The major UK PSPs and their pricing (at time of writing):
| PSP | In-Person Rate | Online Rate | Monthly Fee | Contract | Settlement |
|---|---|---|---|---|---|
| Square | 1.75% | 1.4% + 25p (UK cards) | £0 (free plan) | None | Next working day |
| SumUp | 1.69% | 2.5% | £0 | None | 1-3 working days |
| PayPal POS | 1.75% | 2.5% | £0 | None | Next working day |
| Revolut Reader | 0.8% (Revolut account) / 1.8% (standard) | 1.5% + 20p (Revolut account) | £0 (basic) | None | Instant (to Revolut account) |
| Stripe | N/A (online only) | 1.5% + 20p (UK) / 2.5% + 20p (EU) | £0 | None | 2 working days (configurable) |
The key advantages of PSPs over traditional merchant accounts are speed and simplicity. You can have Square or SumUp accepting payments within the same day you sign up. There’s no credit check, no underwriting interview, and no contract to exit.
But aggregated processing has meaningful trade-offs:
The risk of account holds deserves emphasis. Because PSPs aggregate many businesses under one licence, their fraud monitoring is automated and can be aggressive. If your transaction patterns change suddenly (large one-off sale, new product category, spike in chargebacks), your account can be frozen pending review. With a traditional merchant account, you have a direct relationship with an underwriter who knows your business – which reduces that risk significantly at higher volumes.
PSPs are merchant accounts and payment gateways combined into one product. They’re ideal for most small UK businesses. The trade-off is that you’re a sub-merchant on their licence rather than a direct customer of an acquiring bank – which means slightly less control and slightly higher fees at volume, in exchange for dramatically lower friction.
When Do You Need a Traditional Merchant Account?
You typically need a traditional merchant account once your card turnover exceeds £50,000 per year, when you need Interchange++ pricing, operate internationally, or work in a sector that PSPs won’t underwrite.
The economics of card processing shift decisively at higher volumes. At £50,000/year in card turnover, the difference between flat-rate PSP pricing (1.69-1.75%) and Interchange++ pricing (roughly 0.3-0.6% effective rate for a typical UK card mix) becomes significant – potentially £500-£700 per year, before even factoring in the monthly fees a traditional provider charges.
The specific situations that point towards a traditional merchant account:
- Processing over £50,000/year in card payments. At this volume, Interchange++ pricing almost always delivers net savings even after monthly fees. The break-even varies by card mix, but most businesses find the crossover around £4,000-£5,000 per month in card turnover.
- You need Interchange++ pricing transparency. IC++ separates the interchange cost (set by Visa/Mastercard, regulated by the Payment Systems Regulator), the scheme fee, and the acquirer margin. You see exactly what each layer costs and can negotiate only the acquirer margin. PSPs bundle everything into a flat rate, hiding their actual margin.
- International payments at scale. PSPs typically charge higher rates for non-UK card transactions (1.8-2.5% vs domestic rates). A traditional merchant account with multi-currency acquiring can be significantly cheaper if a meaningful share of your customers are paying with EU or US-issued cards.
- High-risk industry classification. Certain business categories – firearms, adult content, gambling, CBD, pharmaceuticals, subscription-heavy models – are either rejected by PSPs or subject to higher rates and rolling reserves. Specialist high-risk acquirers exist specifically for these sectors.
- You need a dedicated account manager and SLA. PSPs have automated support. Traditional acquirers at mid-market+ volume offer a named relationship manager, negotiable rates, and direct escalation paths. If card payments are mission-critical to your business, having a direct relationship with an underwriter matters.
- You require specific settlement arrangements. Traditional merchant accounts offer more flexibility on settlement timing, multi-currency settlement, and holding structures (useful for marketplaces or businesses with delayed service delivery).
When Is a PSP Enough?
A PSP like Square or SumUp is sufficient for most UK small businesses processing under £50,000 per year in card payments – especially when simplicity, zero monthly fees, and no-contract flexibility matter more than the lowest possible per-transaction rate.
For the vast majority of small UK businesses – sole traders, independents, early-stage companies – a PSP is not just “good enough”; it’s almost certainly the better choice. Here’s when to stay with a PSP:
- You’re processing under £50,000/year in card payments. Below this level, the savings from IC++ typically don’t cover the monthly fees and admin overhead of a traditional account.
- You’re in the early stages. Trading history requirements for traditional merchant accounts can be a barrier. PSPs remove that barrier entirely.
- You want no contract. Traditional acquirers tie you in for 12-36 months with early termination fees. PSPs let you cancel any time.
- You want predictable, simple billing. Flat-rate pricing means your processing cost is always the same percentage. No monthly statement analysis required.
- Your card mix is predominantly UK consumer cards. The IC++ savings are largest when processing premium or business cards (higher interchange). If you mainly take standard UK debit cards, the gap between IC++ and flat-rate narrows considerably.
- You need in-person + online from day one. PSPs like Square offer a fully integrated in-person and e-commerce stack with no technical integration work.
Cost Comparison: PSP vs Traditional Merchant Account
At £20,000/month in card turnover, switching from Square’s 1.75% flat rate to a Worldpay Interchange++ account saves approximately £135-£180 per month, or £1,600-£2,100 per year, net of Worldpay’s monthly fees.
The following worked example uses £20,000/month card turnover, 70% UK consumer debit (Visa/Mastercard), 30% UK consumer credit. These are broadly typical numbers for a mid-size UK retail business.
| Cost Item | Square (PSP, 1.75%) | Worldpay (IC++, estimated) |
|---|---|---|
| In-person transaction fees (70% debit @ regulated IC) | £245 (1.75% × £14,000) | ~£56 (0.4% effective × £14,000) |
| In-person transaction fees (30% credit @ regulated IC) | £105 (1.75% × £6,000) | ~£60 (1.0% effective × £6,000) |
| Terminal rental | £0 (owned outright) | ~£22.50/mo |
| PCI DSS fee | £0 (included) | ~£5/mo |
| Minimum monthly service charge | £0 | ~£15/mo (variable) |
| Payment gateway (if online) | £0 (included) | ~£20/mo (Worldpay Gateway) |
| Total monthly cost | £350 | ~£178-£215* |
| Annual cost | £4,200 | ~£2,140-£2,580* |
*Worldpay figures are estimates based on published rate ranges. Actual rates are quote-based and negotiated individually. The IC++ effective rate varies depending on your card mix, average transaction value, and volume discounts. Figures exclude one-off setup costs and any volume bonuses.
The calculation confirms what the industry rule-of-thumb suggests: above roughly £4,000-£5,000 per month in card turnover, Interchange++ pricing becomes worth investigating. Below that, the monthly fees from a traditional acquirer erode most or all of the rate savings.
The savings from switching to a traditional merchant account at £20,000/month card turnover are real and substantial – around £1,600-£2,000 per year. But the comparison only holds if you also account for all the monthly fees a traditional acquirer charges. Always compare total monthly cost, not just transaction rates.
How to Switch from a PSP to a Merchant Account
Switching from a PSP to a traditional merchant account requires applying to an acquirer, completing underwriting, acquiring new hardware (or reconfiguring existing terminals), and running both systems in parallel during the transition period.
Once your card volume justifies the switch, the process is straightforward but requires planning to avoid revenue disruption:
- Get competing quotes from at least 3 acquirers. Worldpay, takepayments, Elavon, and Barclaycard all have SMB sales teams. Bring your last 3-6 months of processing statements – acquirers use these to calculate your IC++ rate and set your risk profile. Businesses with a clean chargeback history get better rates.
- Understand the full cost structure before signing. Ask for the full schedule of fees: transaction rate, monthly service charge, terminal rental, PCI fee, gateway fee (if online), minimum monthly charge, and early termination penalty. The headline transaction rate is often the least important number.
- Negotiate on contract length. Most acquirers start at 18-36 months. You can often negotiate down to 12 months, especially as a new customer. A shorter initial term reduces your exit cost if a better deal emerges later.
- Plan for hardware. PSP card readers (Square, SumUp, PayPal POS) are locked to their own platforms. A traditional merchant account typically requires different terminal hardware, either rented from the acquirer or purchased outright from a certified supplier.
- Run both systems briefly in parallel. During the first week after switching, keep your PSP account active as a fallback. Terminal configuration issues occasionally delay the first live transactions on a new account.
- Update your payment gateway (if online). If you’re also moving your online payments to a new acquiring relationship, you’ll need to reconfigure your gateway integration. Some acquirers have their own gateways; others integrate with Stripe, Opayo, or other third-party gateways.
One practical point: don’t cancel your PSP account before your merchant account is fully operational and tested. The underwriting process for traditional merchant accounts can take 5-15 working days, and terminal activation can take an additional 2-5 days. Plan a two-week overlap.
For a full comparison of the leading UK merchant account providers, see our best merchant accounts guide. For Interchange++ pricing in detail, see our merchant account costs guide.
Related guides: See our best payment gateways comparison, virtual terminal providers, and best merchant accounts for small business. For a detailed look at Stripe’s gateway capabilities, read our Stripe review.
Our Verdict
For most small UK businesses, a PSP like Square or SumUp is the right choice – no application, no contract, and no monthly fees mean the total cost is lower until your card volume makes Interchange++ pricing worthwhile. That crossover point is roughly £4,000-£5,000 per month in card turnover. If you’re above that, get quotes from Worldpay, takepayments, or Barclaycard, compare the full monthly cost (not just the headline transaction rate), and negotiate on contract length before signing. Don’t overcomplicate the decision early – you can always switch to a traditional merchant account as your volume grows.
