Why this actually matters more than most people think.
I've built and sold five businesses. In almost every one, payment infrastructure was an afterthought at the start and a headache later. A Kent market trader I know was losing around £1,400 a year in fees compared to what she could have been paying — not because she was being careless, but because she signed up for what the market organiser recommended without checking whether it suited her transaction size. It took about twenty minutes to fix once she looked at it properly.
The payment layer touches every sale you make. Getting it right isn't exciting, but it is worth an hour of your attention before you commit to anything.
The four realistic options for a UK small business.
Let me walk through the main providers you'll actually encounter, because the landscape has changed a lot in the past three or four years and a lot of the advice floating around online is either out of date or written for US businesses.
SumUp is where many market traders, sole traders, and food vendors in Kent end up, and honestly, for lower-volume in-person selling it often makes sense. The card reader costs around £39, there are no monthly fees, and the transaction rate sits at 1.69% for most cards. If you're taking £3,000 a month, that's about £51 in fees. Simple, predictable, no contract.
Square is a reasonable alternative at a similar rate (1.75% for in-person), and the free point-of-sale app is genuinely good. Where Square pulls ahead is the ecosystem around it — inventory, online ordering, appointments — so if you're a small retailer or a café that also wants to take orders through a website, Square's joined-up nature can save you paying for two separate systems.
Stripe is the one I've used most across my own businesses, and it's the one I lean toward if you're building anything with an online shop or a website that takes money. The in-person rate is 1.5% + 10p per transaction for UK cards (as of early 2026), which is slightly cheaper than SumUp at moderate volumes. More importantly, Stripe's developer API is miles ahead, and if you ever want a proper online shop, recurring billing, or anything custom, Stripe is where you want to be. The downside: it's more technical to set up if you're not comfortable with software.
Your bank's own terminal — Barclays, Lloyds, HSBC all offer these — is worth a look if you're turning over more than £10,000 a month through card payments. The monthly rental (typically £15–£25) and lower per-transaction rates can work out cheaper at scale. Mind you, the contracts are longer, setup takes weeks not days, and customer service is often glacial. I've seen small businesses get locked into 18-month contracts before they understood what they'd signed. Read everything.
The number that actually tells you which one to use.
Average transaction value. That single number tells you more than anything else about which provider to pick.
If your average sale is under £20 — a sandwich, a coffee, a candle at a Christmas market in Canterbury — the flat percentage providers like SumUp or Square are almost certainly your best bet. No reader cost to recoup, no monthly fee eating into thin margins, done.
If your average sale is over £100 — a tradesperson invoicing for a boiler service, a boutique retailer selling clothing, a therapist taking session payments — the maths shifts. Stripe's slightly lower percentage rate and the availability of payment links (you send a customer a link, they pay by card without needing a reader at all) make it genuinely attractive. A plumber in Deal I know switched to Stripe payment links for invoicing and immediately stopped chasing cheques. His words, not mine.
If you are doing any meaningful volume online, there is really no contest: Stripe or Square's online product. SumUp's online offering exists but it is not where it shines.
What people miss about interchange fees and card types.
This is where it gets slightly tedious but genuinely important. All those headline percentages — 1.69%, 1.75% — apply to standard UK consumer debit and credit cards. The moment someone pays you with a corporate card, or a card issued outside the UK, the rate goes up. Sometimes significantly.
For most small businesses in Kent this isn't a crisis. But if you're selling something that attracts a lot of business buyers — a commercial cleaning firm, a catering supplier, a B2B service of any kind — you'll notice the difference. Stripe is transparent about its blended rates and lets you see what you're actually paying per transaction in the dashboard. Some of the simpler providers are less clear. Worth checking before you commit.
American Express is its own world. Most small business providers either don't accept it or charge a higher rate (typically 2.5%+). If you serve a clientele that tends to put everything on Amex — corporate clients, certain professional sectors — it might be worth accepting it; if not, don't worry about it.
Online shops: what works with what.
If you're building an online shop — and if you're selling products, you probably should be — the payment provider choice and the shop platform choice are linked.
Shopify has its own payments product (Shopify Payments, which runs on Stripe under the hood) and will charge you an extra transaction fee if you use a third-party provider instead. On the basic plan that fee is 2%, which adds up fast. So if you go with Shopify, generally use Shopify Payments unless you have a specific reason not to.
WooCommerce on WordPress works natively with Stripe via a free plugin, and there's no platform-level transaction fee on top. For many smaller Kent retailers building their first shop, WooCommerce plus Stripe is the combination I tend to recommend — you control the code, the costs are transparent, and you're not locked into a platform that will raise its prices when it needs to please investors.
Squarespace and Wix both have their own payment integrations, but they also support Stripe. If you're on either of those platforms, I'd still route through Stripe rather than the platform's native checkout — the reporting is cleaner and you own the relationship with your payment data.
The practical side: getting set up and getting paid.
Whichever provider you choose, you'll need to verify your identity and business before you can withdraw funds. This is standard UK anti-money-laundering practice — they need to know who they're sending money to. Have your passport or driving licence ready, plus a bank statement or utility bill less than three months old. If you're operating as a limited company, Companies House registration details. It usually takes 24–48 hours for verification, occasionally a day or two longer if they want more information.
Payout timing matters more than most people realise when you're starting out. Stripe pays out to your bank account on a rolling 7-day basis by default (you can adjust this once you've built up some history with them). Square is similar. SumUp pays within one to three business days. Some bank terminals pay out next day. If you need cash flow certainty in the early weeks, factor this in — waiting a week for your first batch of payments to clear when you've just spent money on stock is uncomfortable.
One more thing: make sure your trading name on the payment provider matches what you want customers to see on their bank statement. Nothing kills customer confidence like a purchase showing up under a holding company name they've never heard of. I've seen it generate refund requests from perfectly happy customers who thought they'd been scammed.
When to revisit your setup.
It's worth checking your payment costs every six months or so, particularly in the first year or two. Your transaction volume will change, your average order value will change, and the providers' pricing changes too. What was right at £2,000 a month through the till might not be right at £12,000. The calculation takes about ten minutes once you know what you're looking for.
Also worth knowing: if you're building a website with me, I'll include payment integration in the spec conversation from the start. It's one of those things where picking the wrong provider on day one means rebuilding something six months later — and I've done enough of these to know where the traps are.