Knowledge Hub
Acquiring 6 min read

What is a Payment Service Provider (PSP)?

The term "PSP" is used loosely in the payments industry — sometimes to mean a gateway, sometimes an acquirer, sometimes both. Understanding what a PSP actually is, and how it fits into the broader payment stack, is essential for choosing the right partner and avoiding expensive mistakes.

David Sampson · Founder, IceTree

Payment consultant specialising in PSP matching, card acquiring, and high-risk merchant solutions ·

What a PSP Does

A Payment Service Provider enables businesses to accept electronic payments. At its core, a PSP provides the technical infrastructure that connects your checkout — whether online, in-store, or via API — to the banking and card networks that move money.

In practice this means: a checkout integration or payment page, transaction routing and authorisation, fraud screening, a merchant dashboard, settlement reporting, and dispute management. Most PSPs also provide access to multiple payment methods beyond cards — wallets, open banking, buy-now-pay-later, and local payment methods.

PSP vs Acquirer vs Gateway

These three terms refer to different layers of the same payment stack. Understanding the distinction matters when evaluating providers.

Payment Gateway

The gateway is the technology layer — the API or hosted page that captures payment details, encrypts them, and sends the authorisation request onward. A gateway on its own doesn't settle money; it's a pipe.

Acquirer

The acquirer is the licensed financial institution — typically a bank or EMI — that holds your merchant account and receives settled funds on your behalf. The acquirer has the relationship with Visa and Mastercard and is ultimately responsible for the transactions processed under their BIN (Bank Identification Number).

PSP

A PSP typically combines the gateway and acquiring functions — sometimes as a single licensed entity, sometimes by connecting to an underlying acquirer. This is why "PSP" and "acquirer" are often used interchangeably: many modern PSPs are regulated acquirers that own the full stack from integration to settlement.

The simple version

The gateway handles the technical communication. The acquirer holds the money. A PSP usually does both, or connects the two. When someone says "choose a PSP," they mean: choose the company that will handle your payments end-to-end.

Three Types of PSP

1. Full-Stack PSPs

Full-stack PSPs own the gateway, the processing infrastructure, and the acquiring licence. They give each merchant their own merchant account, negotiate individual pricing, and provide dedicated account management for larger clients. Examples include Worldpay, Elavon, and Stripe (for enterprise). Onboarding takes longer — typically 2–6 weeks — but pricing is negotiable and the relationship is more stable.

2. Aggregators

Aggregators pool merchants under a single master merchant account. Stripe, Square, and SumUp are the best-known examples. Onboarding is fast, integration is excellent, and no underwriting is required upfront. The tradeoffs are higher flat rates (typically 1.4–2.9%), limited ability to negotiate, and the risk of account holds or terminations when the aggregator's automated risk systems flag an account.

3. White-Label / BaaS PSPs

Some providers offer payment infrastructure as a building block — APIs and banking rails that other businesses sit on top of, including other PSPs. These are increasingly relevant for platforms and marketplaces that want to embed payments natively. Pricing is typically volume-based and requires deeper integration work, but the commercial and technical control is greater.

Pricing Models

PSP pricing typically takes one of three forms:

  • Blended / flat rate. One percentage for all card types (e.g. 1.4% + 20p). Simple, but opaque — cheaper debit transactions subsidise more expensive credit and premium cards.
  • Interchange-plus (IC++). Pass-through interchange and scheme fees, plus a fixed acquirer markup. Transparent, typically cheaper at volume. The markup is the only negotiable component.
  • Interchange-plus-plus with fixed per-transaction fees. As above but with an additional fixed fee per transaction (e.g. £0.02). Relevant for merchants with low average order values where percentage-based pricing is misleading.

What to Look for in a PSP

  • Authorisation rates. The percentage of transactions that are approved. A 1% difference in auth rate at £500k/month is £5,000/month in lost revenue. Ask for benchmarks for your vertical.
  • Settlement timing. How quickly funds reach your bank account — typically T+1 to T+3. Faster settlement matters for cash-flow-intensive businesses.
  • Chargeback handling. What tools and support are available for dispute management? A poor chargeback process adds operational cost and can threaten your merchant account.
  • Payment method coverage. Do they support the methods your customers actually use — not just Visa and Mastercard, but wallets, local methods, and open banking?
  • Contract terms. Minimum volume commitments, rolling contracts, and termination fees can make a cheap rate expensive in practice. Read the contract.

When to Switch PSP

The most common triggers for a PSP switch:

  • Volume has grown past the flat-rate aggregator breakeven (typically £10–50k/month depending on margin)
  • Authorisation rates are below industry benchmarks and the PSP can't explain why
  • The business has expanded internationally and the current PSP doesn't support those currencies or methods
  • The contract is up for renewal and comparable providers are offering materially better terms
  • Account holds or reserves are impacting cash flow

Before you switch

Get at least two competing term sheets before entering any negotiation. Your current PSP will almost always offer better terms when they believe you're genuinely about to leave. The offer they make at that point is usually closer to the market rate than what they gave you at onboarding.

FAQ

Common questions answered.

A Payment Service Provider is a company that enables businesses to accept electronic payments — card, bank transfer, wallet, and more. A PSP connects your checkout to the wider payment network, handling authorisation, settlement, and fraud screening. Some PSPs bundle acquiring (the bank account that receives funds) with their gateway and processing, while others focus on one layer.

An acquirer is the bank or financial institution that holds the merchant account and actually settles funds into it. A PSP is typically the technology layer that sits above the acquirer — routing transactions, handling the API, and managing the merchant dashboard. Many modern PSPs are also licensed acquirers themselves, which is why the terms are often used interchangeably. When they are separate, your PSP connects to an acquirer behind the scenes.

A payment aggregator (like Stripe or Square) pools merchants under a single master merchant account rather than giving each merchant their own account. This makes onboarding fast — sometimes instant — but means you're sharing infrastructure with thousands of other merchants. The tradeoff is higher flat rates, less negotiating power, and occasional account holds when the aggregator's fraud models flag unusual activity.

Consider switching when: your processing volume has grown past the threshold where flat-rate aggregator pricing becomes expensive (roughly £10–50k/month); you're experiencing unexplained declines or poor authorisation rates; you need payment methods your current PSP doesn't support; or your contract is up for renewal and you haven't tested whether better terms are available elsewhere. Switching PSPs is disruptive but often worth it.

Aggregators (Stripe, SumUp) can onboard in minutes. Traditional acquiring banks typically take 2–6 weeks, depending on business complexity, jurisdiction, and documentation quality. High-risk verticals may take longer. The fastest traditional onboarding IceTree has facilitated was 4 business days for a low-risk UK e-commerce merchant with complete documentation.

Not sure if your PSP is right for you?

We'll review your current setup and tell you plainly whether you're on competitive terms — or whether a switch would save you money and improve performance.

Free Rate AuditCard Acquiring Services

We use cookies to analyse site performance and measure the effectiveness of our outreach. Privacy policy