Payment Gateway Fees Explained for UK Online Businesses
Understand how gateway, processing and ecommerce platform charges fit together before comparing online payment quotes.
The short answer
A payment gateway handles payment information between checkout and the payment service. Its price may be bundled into processing or charged separately. Compare the complete stack: processing, gateway requests, subscriptions, platform transaction charges and other relevant costs. A lower processing percentage alone does not establish a cheaper online checkout.
In this guide
Separate the services before adding their prices
| Cost layer | What to establish |
|---|---|
| Payment processing | Percentage and fixed fees for the relevant card groups and currencies. |
| Gateway | Whether included, billed monthly or charged per request or transaction. |
| Ecommerce platform | Subscription and any extra charge triggered by the payment-provider choice. |
| Additional services | Fraud tools, billing, currency conversion or other features actually required. |
Shopify’s gateway information describes different provider fee structures. Its Help Centre also confirms that applicable third-party transaction fees are additional to the external provider’s processing charges. Eligibility and exceptions depend on the setup, so do not apply a platform fee indiscriminately to every payment.
Check what triggers each fixed charge
A successful order, a payment attempt, an authorisation request and a refund are different events. A fee quoted per gateway request may not use the same count as a fee per completed sale. Ask what happens when a customer retries after a decline or an order is cancelled.
- Confirm the fee unit and which successful or unsuccessful events are chargeable.
- Check monthly included allowances, minimums and overage charges.
- Ask whether authentication, saved-payment or recurring-billing tools add fees.
- Establish the card categories, currencies and countries covered by the headline rate.
- Check whether original processing, gateway and platform fees are returned after a refund.
Use the authorisation and per-transaction fee guide to keep different request counts visible.
Worked example: the missing platform layer
Fictional offers. Assume £20,000 of eligible monthly online sales in 500 successful payments. Each payment creates one chargeable gateway event, with no failures or refunds.
| Cost | Bundled offer | Separate gateway offer |
|---|---|---|
| Processing percentage | 1.6% = £320 | 1.2% = £240 |
| Fixed processing fee | 500 × 20p = £100 | £0 |
| Gateway event fee | Included | 500 × 5p = £25 |
| Gateway monthly fee | Included | £25 |
| Additional platform transaction fee | £0 | 0.8% = £160 |
| Monthly total | £420 | £450 |
Before the platform charge, the separate offer appears £130 cheaper at £290 monthly. With the £160 platform fee, it costs £30 more each month, or £360 more over twelve identical months.
Only include a platform charge where the actual plan and payment configuration trigger it. If no such charge applies, the comparison changes. Add setup, migration and any different software subscription before deciding.
Compare equivalent checkout functions
Make sure both offers support the payment methods, currencies, recurring billing and refund process you need. Check how payment status reaches the order system, who supports checkout failures and whether saved payment methods can be migrated through an approved process.
A hosted checkout and a custom integration can create different development and support costs. A rate reduction may be worthwhile, but budget for implementation, testing and any overlap with the old provider. See online shop payment costs for the wider comparison.
Use the calculator without merging unlike fees
Enter the online sales and successful payment count for the processing tariff. Add recurring gateway or platform subscriptions to the appropriate monthly cost fields. Combine percentage or per-payment charges only where they apply to exactly the same sales base and event count.
Keep gateway attempts, refunds, tiered allowances and any differently defined platform fee in separate workings if the calculator cannot represent the rule directly. Do not add a gateway charge twice when it is already included in the provider’s bundled price. Ask for an example invoice using your expected sales and request counts.
Common questions
Is a payment gateway fee the same as a processing fee?
Not necessarily. Some providers bundle gateway functionality into processing; others charge separately. Check what each line covers before adding or comparing it.
Can changing gateway increase the ecommerce platform bill?
It can where the platform applies additional charges to the chosen payment arrangement. Check the current plan, provider combination and exceptions in writing.
Put your own figures to work.
Use the free calculator to organise your costs and keep a report. If something is unclear, you can ask for a free initial review.
No registration required. Calculator entries stay in your open browser page unless you choose to share a report in a review request.
Sources and how to use this guide
Primary references checked on 15 October 2026:
- Shopify UK: payment gateways and fee structures
- Shopify: third-party transaction fees and processing charges
Worked examples are original fictional scenarios, not customer results, market averages or provider quotations. Unless stated otherwise, they use a consistent VAT basis and include only the costs listed. Provider prices, eligibility and terms can change. Check your written agreement before deciding.
Our guides explain costs and comparison methods. They do not rank the whole market or claim hands-on product testing. Source links are references, not a claim of partnership. Read the calculation method and limitations, or about the service.
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