Card acceptance is a chain, not one service. A merchant or its gateway sends an authorisation to the acquirer; the card scheme routes it to the issuer; clearing calculates obligations; and settlement moves net funds. The merchant service charge normally recovers several layers: interchange passed to the issuer, scheme and processing fees charged by the network, the acquirer’s risk and operating margin, and sometimes gateway, terminal, PCI, fraud, foreign-exchange and chargeback costs. Blended pricing hides much of that mix; interchange-plus-plus exposes more components but does not make them simple. UK rules cap qualifying domestic consumer interchange in four-party schemes, subject to scope and exemptions, but do not impose one all-in merchant price. The PSR’s 2021 card-acquiring review found weak outcomes for merchants with annual card turnover below £50 million. Its remedies added summary information, online quotes, contract-end prompts and an 18-month maximum for point-of-sale terminal contracts among directed firms. A separate 2025 review found Mastercard and Visa’s core scheme and processing fees to acquirers rose by more than 25% in real terms between 2017 and 2023, costing at least £170 million more annually; transparency, pricing-governance and financial-reporting remedies remain in development at the August 2026 review date. The PSR also found UK–EEA online interchange increases cost merchants £150–200 million a year, but it abandoned an interim cap and is developing a durable methodology. Merchants should optimise total effective cost and acceptance quality, not headline percentage alone.
Every card sale produces one customer experience and several wholesale prices. The receipt may show £100, while the merchant receives less after interchange, network, acquiring and ancillary charges. Those charges respond to card type, channel, geography, authentication, risk, volume and contract. Treating the difference as a single ‘Visa fee’ or ‘processor fee’ prevents meaningful comparison.
This guide follows the economics beneath the UK payments map and complements the case studies on enterprise acquiring and bank-payment alternatives. It separates scheme rules from acquirer service, regulated interchange from unregulated line items, and final PSR remedies from proposals that had not yet taken effect in August 2026.
Who receives interchange?
The issuer receives it through the card-system chain; the acquirer normally passes the amount through as part of what it charges the merchant.
Does the interchange cap limit the whole merchant service charge?
No. It applies to specified interchange, not every scheme, processing, acquirer, gateway, terminal, fraud, FX or chargeback cost.
What is the best comparison metric?
Calculate effective total cost by transaction cohort, then compare authorisation, fraud, chargeback, settlement, reporting and contract outcomes alongside price.
What does a card acquirer actually provide?
An acquirer enables a merchant to accept card transactions and receives settlement from the scheme on the merchant’s behalf. It contracts with the merchant, submits or sponsors transactions into card networks, funds merchant payouts and manages exposure to refunds, disputes, fraud and failure to deliver. The acquiring legal entity may also provide the gateway and processing stack, or those functions may be supplied by separate technology firms.
The acquirer is not the card scheme. Visa and Mastercard establish network rules, route messages and calculate scheme settlement, while banks and other licensed participants issue cards or acquire merchants. Three-party schemes can combine more roles. A payment facilitator or marketplace may aggregate sub-merchants under a master arrangement, but the risk allocation, onboarding and payout structure still has to connect to an acquiring participant.
How does a sale move from authorisation to settlement?
At authorisation, the merchant sends card and transaction data through a terminal or online gateway to the acquirer or processor. The scheme routes the request to the issuer, which applies funds, fraud and authentication logic and returns an approval or decline. An approval reserves or confirms capacity; it is not final cash settlement and can later be reversed, expire or become disputed.
The merchant captures the transaction and submits it for clearing. Network files identify interchange and other obligations, after which settlement banks move net positions and the acquirer pays the merchant according to its schedule. Refunds and chargebacks travel through related but distinct messages. The period between a merchant receiving proceeds and final exposure ending creates credit and liquidity risk that the acquirer prices, reserves or secures.
What is inside the merchant service charge?
The merchant service charge, sometimes described through a merchant discount rate, is the principal fee for acceptance. Its wholesale base often includes interchange and scheme or processing fees; the acquirer adds margin for technology, operations, funding, compliance, fraud, credit and service. A percentage plus a fixed authorisation or transaction amount means small-ticket economics can differ substantially from the advertised percentage.
Other amounts can sit inside the rate or appear separately: gateway subscriptions, terminal rental, tokenisation, 3-D Secure, network assessments, PCI non-compliance, currency conversion, cross-border uplift, refunds, retrievals and chargebacks. Pricing can also include minimum monthly charges or tiered volume commitments. A merchant should reconcile gross sales to net payout and invoice rather than assume all deductions appear in one contract table.
How does interchange shape issuer and merchant economics?
Interchange is transferred from the acquiring side to the issuer for a card transaction. It helps fund issuance, fraud losses, processing, credit and rewards, but it enters the merchant’s cost through the acquirer. The rate varies by scheme schedule and transaction attributes, including consumer or commercial card, debit or credit, domestic or cross-border status and card-present or card-not-present channel.
The UK Interchange Fee Regulation caps interchange for qualifying domestic consumer four-party transactions at 0.2% for debit and 0.3% for credit. Scope is decisive. Commercial cards, certain three-party arrangements and cross-border corridors can fall outside or receive different treatment. The cap constrains the issuer transfer, not the scheme’s own fees or the acquirer’s all-in charge, so a low interchange line does not prove a competitively priced merchant contract.
What are scheme and processing fees?
Schemes charge for participation, brand and rulebook services, message processing, clearing, settlement and a catalogue of transaction or service attributes. Some charges are core and unavoidable for a given flow; others relate to optional or behavioural services. Fee schedules can combine percentages, fixed amounts, tiers, thresholds and incentives. Acquirers must translate that complexity into merchant pricing while managing later scheme changes.
The PSR’s March 2025 final report found Mastercard and Visa did not face effective competitive constraints in supplying core scheme and processing services to UK acquirers. It found real-terms core fees rose by more than 25% from 2017 to 2023, adding at least £170 million per year, and that unclear or incomplete information raised acquirer and merchant costs. Those findings concern network economics, not proof that every individual charge or merchant price is unlawful.
Where do gateways, processors and payment facilitators fit?
A gateway securely collects payment data and connects the merchant environment to processing. A processor formats, routes and records authorisation or clearing messages. Token providers, fraud engines and orchestration platforms can add services across multiple acquirers. An integrated provider may perform all these roles plus acquiring; another may supply software while a partner institution remains the contractual acquirer and settlement-risk owner.
A payment facilitator simplifies access for smaller sellers by onboarding them as sub-merchants and aggregating flows. That model creates platform-level responsibility for know-your-customer checks, transaction monitoring, reserves, prohibited activity and payout controls under its acquiring contract. Merchants should identify who holds funds, who appears on statements, who can withhold settlement and who receives a dispute. A single dashboard can conceal several legal entities and fee schedules.
Blended, interchange-plus and IC++ pricing compared
Blended pricing offers one or a few headline rates across categories. It is easy to budget but combines wholesale cost and margin, so the acquirer benefits or loses as the merchant’s mix changes. Interchange-plus separates the applicable interchange from an acquirer markup. IC++ goes further by exposing interchange, card-scheme fees and acquirer margin as distinct layers, although hundreds of underlying network lines can still be grouped or allocated.
No model is universally cheapest. A simple retailer can value a stable blended rate; a large or international merchant may need IC++ data to route, forecast and negotiate. Comparison requires a representative transaction file and consistent inclusion of fixed fees, refunds, cross-border and ancillary services. Repricing only the visible markup may have little impact if card mix, scheme assessments, failed authentication or low average ticket drives most of the effective cost.
Merchant card-cost stack
A useful invoice model assigns every amount to an economic owner and controllability category. Some costs are regulated or scheme-set, some are negotiable provider margin, and others can be influenced through routing, authentication, data quality or fraud performance. The table avoids the common error of treating every line as interchange.
What did the card-acquiring market review find?
The PSR’s 2021 final report concluded that acquiring did not work well for small and medium merchants and larger merchants with annual card turnover up to £50 million. Merchants with £15,000 to £50 million of annual card turnover served by the five largest acquirers received little or no pass-through of savings from interchange caps. Many merchants rarely searched, negotiated or switched even where savings were available.
The finding was not that one provider or price should serve every merchant. Search friction, opaque statements, contract complexity and terminal lock-in weakened the competitive process. In response, the PSR directed 14 significant providers through Specific Directions 14, 15 and 16, later updating the directed-entity mechanism. The directions target information and switching conditions rather than setting a universal merchant service charge.
How do the PSR’s acquiring remedies work?
Directed providers must supply a standard summary information box and an online quotation tool so merchants can obtain more comparable information. Trigger messages alert merchants when an initial contract or subsequent period ends and encourage them to shop around. Point-of-sale terminal lease and rental contracts are capped at 18 months, followed by a rolling monthly arrangement, reducing long equipment lock-ins.
The remedies can improve negotiation only if merchants use the information and compare like with like. An online quote based on standard assumptions may differ from realised cost when card mix or services change. The PSR continues to monitor how easy tools are to find, whether quote and actual prices align, whether trigger messages prompt action and whether terminal exit works. Contract renewal should therefore start with actual transaction and invoice data, not the trigger message alone.
What remedies are proposed for scheme and processing fees?
Following its scheme-fee findings, the PSR consulted in 2025 on three remedy areas: better information and transparency, stronger governance around scheme pricing, and regulatory financial reporting. At the August 2026 review date, the PSR said it expected to publish final directions for information/transparency and pricing governance later in 2026, while CP26/1 consulted on a draft financial-reporting direction.
That status matters. The final market-review findings are established, but draft directions should not be described as binding until adopted and commenced. Acquirers still need to manage current scheme schedules, pass-through clauses and merchant communications. Better network data could improve forecasting and challenge, yet a regulatory report by itself does not lower a fee; any commercial or regulatory effect depends on final design and subsequent market behaviour.
Why are UK–EEA online interchange fees a separate issue?
After the UK’s EU exit, Mastercard and Visa increased outbound interchange on EEA-issued consumer cards used for card-not-present purchases at UK merchants. The PSR reported increases from 0.2% to 1.15% for debit and from 0.3% to 1.5% for credit during 2021 and 2022. Its December 2024 final report found the fees unduly high and estimated £150–200 million of additional annual cost to UK businesses.
The regulator initially considered an interim cap followed by a lasting methodology. It later decided not to proceed with the interim cap and instead to develop the robust methodology first. The High Court upheld the PSR’s power to regulate these fees, but that judgment did not itself set a price. As of August 2026, merchants should model the current corridor cost and monitor formal decisions rather than book an assumed cap saving.
How should a merchant evaluate an acquiring proposal?
Build a twelve-month cohort model by scheme, consumer or commercial type, debit or credit, domestic or cross-border status, channel, currency, ticket size and refund rate. Apply each proposal’s percentages, fixed fees, minimums, rentals and ancillary charges to the same file. Divide total cost by settled sales for an effective rate, but retain the pence-per-transaction view because average ticket can make percentage comparisons misleading.
Then score non-price outcomes: authorisation uplift, false declines, fraud and chargeback liability, payout timing, reserves, reconciliation, reporting, support, data portability, outage history and termination. A provider that appears ten basis points cheaper can be more expensive if conversion falls or cash is delayed. Contract controls should specify notice of scheme changes, audit evidence, subprocessor dependency and rights to route or exit.
How do acquirers manage unit economics and failure risk?
An acquirer’s net revenue is the merchant charge less interchange, scheme fees and other pass-through costs. Against that spread sit processing, fraud tools, compliance, sales, support, funding and losses. Large merchants bring volume and thin margins; small merchants can support more margin but require proportionally more onboarding and service. Cross-border and higher-risk verticals can increase both price and reserve or collateral requirements.
The key balance-sheet risk is that the merchant cannot meet refunds or chargebacks after it has already received settlement. Acquirers monitor delivery periods, concentration, dispute rates and financial health, then use delayed settlement, rolling reserves, guarantees or limits. Abrupt holds can damage a healthy merchant, while weak reserves can damage the acquirer. Risk policy therefore has to be explainable, contractually grounded, sensitive to forward obligations and supported by a fair review and escalation process.
Will pay-by-bank or regulatory consolidation remove card costs?
Open-banking payments can offer merchants an account-to-account route with a different cost and risk stack. They do not automatically replicate card reach, consumer protections, recurring credentials, refunds or dispute experience. The commercial opportunity is selective routing: use the method that fits the customer journey and liability rather than assuming one rail replaces every card transaction. The open-banking guide maps that alternative.
Government intends to transfer PSR functions into the FCA through primary legislation. Until commencement and transition are complete, the PSR remains the relevant authority and its directions continue to bind their addressees. An organisational change does not erase the economics or competition issues. Merchants, acquirers and schemes should track final legal instruments, not infer that consultation, a court judgment or a proposed regulator structure has already rewritten invoices.
Frequently Asked Questions
Is the merchant service charge the same as interchange?
No. Interchange is one wholesale component. The merchant service charge can also recover scheme, processing, acquirer and ancillary service costs.
What is IC++ pricing?
It presents interchange, card-scheme charges and acquirer markup as distinct layers. It improves visibility but still requires careful allocation of complex scheme lines and fixed costs.
Are card-terminal contracts limited to 18 months?
Specific Direction 16 imposes that limit, followed by a rolling monthly arrangement, on the directed providers and relevant POS terminal lease or rental contracts. Check the provider, service and current direction.
Has the PSR capped UK–EEA online interchange fees?
Not at the August 2026 review date. It found harm and is developing a lasting-cap methodology after deciding not to impose the proposed interim cap.
Will the FCA replace the PSR immediately?
No. Government plans primary legislation and transition. Current PSR rules, directions and responsibilities continue until formally transferred or changed.
Primary Sources and Further Reading
This guide prioritises regulators, payment-system operators and company filings. Figures are the latest available at the August 2026 review date.
- PSR — Card-acquiring market review final report
- PSR — PS22/2 card-acquiring remedies final decision
- PSR — Card-acquiring remedies monitoring
- PSR — Card scheme and processing fees market review
- PSR — Scheme and processing fees final findings
- PSR — CP25/1 scheme-fee remedies consultation
- PSR — Cross-border interchange-fee market review
- PSR — Decision not to proceed with an interim cross-border cap
- PSR — High Court decision on cross-border fee powers
- UK legislation — Interchange Fee Regulation
- HM Treasury — Streamlined payment-systems regulation response
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