What is affiliate marketing? A beginner's guide to how it works in the UK

Affiliate marketing is when a business pays other websites, apps or creators a commission for each sale or lead they refer. Every referral is tracked through a unique link or code, so the business pays for results rather than for advertising space. It's a major UK channel: brands spent £1.8 billion on affiliate and partner marketing in 2025, generating £20.7 billion in tracked revenue, according to the APMA's State of the Affiliate Nation report (InPublishing, 2026).

This guide is mainly for UK businesses weighing up the channel, rather than would-be bloggers, and there's a dedicated section for anyone hoping to become a publisher. Whether affiliate marketing adds real profit or quietly leaks margin rarely comes down to the idea itself. It comes down to detail: how commission is structured, which publishers are recruited and how sales are tracked and validated. The sections below explain each in plain English.

Key takeaways

• Affiliate marketing is a performance-based channel: advertisers pay publishers commission only when a tracked sale, lead or other agreed action happens.
• Four core parties make it work: the advertiser, the publisher, the network that tracks and pays, and the customer. Many advertisers add a fifth, an agency, to run the programme.
• It's a major UK channel, with £1.8 billion of advertiser spend and £20.7 billion of tracked revenue in 2025.
• Accurate tracking in 2026 depends on first-party data, valid consent and server-to-server integration, not browser cookies alone.
• Publisher mix, clear terms and careful validation matter more than the headline commission rate.

What is affiliate marketing?

Affiliate marketing is a form of performance marketing in which a business pays independent partners a commission for each sale, lead or other agreed action they refer. The business is called the advertiser, and the partner is called the affiliate or publisher. Every referral is tracked through a unique link or code. As a result, the advertiser pays for outcomes rather than for impressions or clicks.

Imagine a UK homeware retailer that agrees to pay 8% commission on kitchen appliance sales. A review site recommends one of its kettles and a reader clicks the tracked link and buys. Once the returns window closes, the retailer pays the site 8% of the order value. If nobody buys, the retailer doesn't pay anything for the exposure.

You'll also see the channel called affiliate advertising, partner marketing or partnership marketing. The terms overlap heavily, although "partnership marketing" usually signals deals that go beyond standard commission, such as brand-to-brand collaborations.

How big is affiliate marketing in the UK?

Affiliate marketing is a mainstream UK channel, and it's still growing. The APMA's third State of the Affiliate Nation report, built on data from 11 networks plus modelling, found that brand spend rose 7.3% to £1.8 billion in 2025. Tracked transactions reached 357 million, or roughly 41,000 every hour (InPublishing, 2026).

Retail accounted for 47% of spend, but the channel reaches well beyond retail. Travel spend grew 14%, and telecoms programmes added around one million new customers a month. Over Cyber Weekend, £1 in every £7 spent was tracked through an affiliate link, up from £1 in every £8 in 2024.

Who is involved in affiliate marketing?

Four core parties are involved in affiliate marketing: the advertiser, the publisher, the affiliate network and the customer. Many programmes add a fifth, an agency, to run things day to day. The table below summarises each role, with familiar UK examples.

Advertisers: the businesses paying for results

Advertisers are businesses that sell online and want more customers on a pay-for-performance basis. They span almost every sector, from fashion and travel to broadband, insurance and software. An advertiser decides what it'll pay for, how much and under what rules, then checks each sale is genuine before releasing commission. Our page for advertisers explains how we support brands at each stage.

Publishers: the partners who reach the customer

Publishers are the websites, apps and creators that promote an advertiser to their own audiences. Content publishers, such as newspapers and review sites, influence customers early in their research. Voucher code and cashback sites usually reach customers close to purchase, while price comparison sites sit in between.

The category also includes social media creators, email marketers, key worker discount schemes and technology partners that add features to a checkout. Each type converts differently and deserves different terms, so it's a mistake to treat them as one uniform group in a new programme. After EngageMore restructured DASH Water's commission groups and discount codes by publisher type, revenue rose 28% year on year. Sale-contributing publishers rose 48% year on year in the quarter, as the DASH Water case study shows.

Affiliate networks and platforms: the infrastructure

An affiliate network sits between advertiser and publisher. It provides the tracking technology, records each click and conversion, and gives both sides a dashboard for viewing and validating results. Networks also invoice the advertiser and pay publishers, and most offer a ready-made pool of publishers to recruit. Our round-up of the top affiliate networks in the UK compares the main options.

Agencies: optional, but common

Many advertisers hand day-to-day management to an agency or to the network's account team. The job is to set strategy, recruit and negotiate with publishers, police compliance and report on what's genuinely incremental. Our guide on how to choose an affiliate marketing agency sets out the trade-offs, and our affiliate programme management service shows what that support involves.

Customers: the reason the model works

The customer never signs an affiliate agreement, yet every part of the model depends on them. They decide whether to trust a recommendation, accept tracking cookies and complete a purchase. Programmes that lean on misleading content can win short-term sales while eroding the trust that makes affiliate recommendations convert.

How affiliate marketing works, from click to commission

Affiliate marketing works in two stages: a tracked link records the customer's click and purchase, then the advertiser validates the sale and the network pays the publisher. The diagram below maps how advertisers, publishers and networks connect, and the sections that follow walk through the journey in order.

From click to tracked sale

Every publisher receives unique tracking links, known as affiliate links, that identify them. When a customer clicks one, the network records the click and sends the customer to the advertiser's site with a click ID added to the web address. The advertiser's site stores that ID, typically in a first-party cookie, so the visit can be matched to a later purchase.

When the customer buys, the advertiser's site tells the network about the order, including its value and the click ID. Traditionally this happened through a tracking pixel on the confirmation page. Increasingly, it also happens server-to-server, as we'll explain below. The network then credits the right publisher and records the commission as pending.

From pending to paid

A tracked sale isn't yet a paid commission. First, the advertiser validates the transaction, confirming it was genuine and not returned or cancelled. Validation periods vary by sector. Some travel companies only validate a booking once the customer has travelled, which can be months later.

Next, the network invoices the advertiser, usually monthly, for validated commission plus its own fee. Payment terms are often around 30 days, and publishers generally aren't paid until the network has received the funds. Their balance must also pass the network's payment threshold. For a new publisher, that chain can mean waiting several months for a first payout.

Why some affiliate commissions are declined

Even a correctly tracked sale can be declined, usually because of a return, a discount code that wasn't issued to the channel or a breach of programme terms. Returns and cancellations are the most common reason, as commission on a returned order is normally reversed. Publishers in high-return categories such as fashion should expect a gap between tracked and approved earnings.

Discount codes are the second big cause. A customer may use a code never issued to the affiliate channel, such as one from the advertiser's own email campaign. In that case the advertiser may decline the commission because it credits the sale elsewhere. Likewise, if one publisher's exclusive code is used after another publisher's click, the sale may be reallocated.

The third cause is a breach of programme terms. The classic example is a publisher bidding on the advertiser's brand name in Google Ads, capturing sales the advertiser's own search activity would have won anyway. Clear, published terms protect both sides.

Affiliate commission models compared

Publishers can be paid a share of each sale, a fixed fee per sale or lead, a fee per click, a fixed placement fee or a mix of these. The choice shapes how they promote you, so it's one of the first decisions an advertiser makes. The most common structure is cost per action (CPA), but it's far from the only one. According to the APMA, close to one pound in five spent in 2025 went on non-CPA payments such as click fees, tenancies and hybrid deals (InPublishing, 2026). The table below compares the main models.

On top of publisher commission, networks typically charge advertisers a fee, often a percentage of the commission paid, and some add set-up or monthly platform fees. Build these into your target cost per sale from the start. Our guide to structuring affiliate commissions covers tiered and category rates in more depth.

How affiliate tracking works in 2026

Affiliate tracking in 2026 works by storing a click ID, usually in a first-party cookie or on the advertiser's server, and matching it to the sale, with the customer's consent. It's the part of the channel that's changed most in recent years, so many beginner guides are now out of date. Browsers, privacy law and consent tools all affect whether a sale is credited to the right publisher.

Cookies and cookie duration

Most affiliate tracking relies on first-party cookies, set on the advertiser's own domain, rather than third-party cookies. Each programme sets a cookie duration, often 30 days, which is the window in which a purchase can be credited to the referring publisher. In practice, though, it's the browser that decides how long it survives.

Apple's Safari is the strictest. Its Intelligent Tracking Prevention blocks all third-party cookies and deletes cookies created by JavaScript after seven days without user interaction with the site. Where it detects click IDs added to a link, it caps cookies created by JavaScript on the landing page at 24 hours, according to WebKit's tracking prevention documentation. With iOS 26, Apple also extended advanced fingerprinting protection to all Safari browsing by default (Apple, 2025).

Google Chrome, by contrast, still supports third-party cookies. In April 2025, Google confirmed it would keep its current approach and not roll out a standalone cookie prompt (Google Privacy Sandbox, 2025). That matters less than it sounds, because Safari's restrictions apply whatever Chrome does.

Consent and UK privacy law

Under the Privacy and Electronic Communications Regulations (PECR), non-essential cookies have long required consent in the UK. From 5 February 2026, the Data (Use and Access) Act 2025 added exceptions for cookies used solely for statistics, website appearance and emergency assistance (Womble Bond Dickinson, 2026). None of these is aimed at advertising, so it's safest to treat affiliate tracking as needing consent unless your legal adviser concludes otherwise.

In practice, a customer who rejects cookies often won't be tracked in the usual way. Test how your consent banner and network tags interact. A misconfigured banner can block tracking even for customers who did consent, costing publishers commission and costing you their goodwill.

Server-to-server tracking

Server-to-server tracking reduces dependence on the browser. The advertiser's server records the network's click ID when the customer lands, then sends the order details directly to the network when they buy. Awin, for example, asks advertisers to store its click ID in a cookie set by the server, using the HttpOnly and Secure flags (Awin developer documentation).

That matters because Safari's seven-day and 24-hour caps target cookies created by JavaScript. First-party cookies set by the server aren't capped in the same way, unless third-party CNAME or IP cloaking is involved. Server-to-server tracking doesn't remove the need for consent, but it keeps tracking working when browser tags are blocked or fail to fire.

Why sales go untracked

Lost sales often trace back to implementation rather than browsers. Typical faults are landing pages missed during set-up, a conversion tag on the wrong page, or a master tag that only loads under faulty conditions. Each one silently leaks tracked sales, and publishers usually notice before advertisers do.

Customer behaviour causes much of the rest. A shopper might research on a phone and buy on a laptop, or complete the purchase in an app with no tracking. Broken publisher links create further gaps. Regular audits, with test transactions across devices and browsers, catch most of these problems early.

Attribution: who gets the credit

Attribution decides which publisher is paid when more than one was involved. Most UK programmes still use last click, so the final affiliate click before purchase earns the full commission. Some advertisers now share commission across the journey, rewarding the content publisher that introduced the customer as well as the site that closed the sale.

Advertisers also deduplicate. A sale may be removed from the affiliate channel if the last click came from the advertiser's own paid search or email. Whatever rules you choose, publish them in your programme terms so publishers can judge whether promoting you is worthwhile.

Getting started with affiliate marketing as an advertiser

Starting affiliate marketing as a UK advertiser comes down to six commercial decisions, and they're worth settling before you switch on a network. They cover what the channel is for, the budget, your publisher mix, your offer to publishers, the rules and who'll run the programme.

Decide what the channel is for

Start with objectives, such as new customers, overall sales volume, a new category or clearing ageing stock. Each goal points to different publishers and commission levels. Map how affiliates will interact with SEO, paid search and email too, because overlaps create duplicated costs. Our guide to how a well-run affiliate programme complements other channels covers this in depth.

Plan the budget, even though you pay on results

In theory, a channel that only pays on results funds itself. In practice, finance teams need forecasts, and network fees, tenancies and incentives all add up. Set a monthly budget and a target cost per sale before launch, so a strong month is a welcome surprise rather than a cash flow problem.

Choose your publisher mix

Decide which publisher types fit your brand and objectives. A premium brand might prioritise editorial partners and limit discount sites, while a challenger chasing volume might lean on cashback and comparison. Most healthy programmes blend several types, then rebalance towards those bringing genuinely new customers.

Constraints shape the mix too. Carwow can't offer discounts, so EngageMore worked with closed user groups (members-only schemes such as Blue Light Card) using e-vouchers through Giftcloud, and introduced email publishers on a cost-per-lead model. It also analysed subnetworks to keep only appropriate partners, as the Carwow case study describes.

Make the programme worth promoting

Publishers choose where to spend their time and placements, so you're competing for their attention. Brand strength, pricing and conversion rate matter as much as commission. Publishers also look for exclusive offers, incentives, an accurate product feed, fresh creative and early notice of promotions.

Set clear rules and stay compliant

Your programme terms should state what publishers may and may not do, typically covering brand bidding, unauthorised discount codes and email promotion. Compliance is also a shared duty. The ASA treats affiliates as secondary advertisers. Both brand and affiliate are responsible for making ads obviously identifiable, even when the affiliate created the content (ASA, 2023).

Choose your platform and who will run it

Most UK advertisers launch on a network for its tracking, payments and publisher base, though larger brands sometimes use a partnership platform. Someone then has to handle set-up, recruitment, validation and compliance every week, whether that's your team, the network or an agency. Our guide to choosing the right affiliate marketing services explains the options. Once you're live, our article on how to scale an affiliate marketing programme covers the next stage.

Getting into affiliate marketing as a publisher

To become an affiliate publisher, build an audience that trusts you, join a network, then apply to advertiser programmes that suit that audience. The fundamentals mirror the advertiser side, but the priorities aren't the same.

Build the audience before the links

Choose a model and a niche you can serve credibly, whether reviews, deals, comparison or social content. Then decide how you'll grow traffic, through SEO, paid media, email or social. Networks and advertisers look for an established audience, so applications from brand-new sites are often declined.

Join networks and programmes

The usual route is to join a network, then apply to individual advertiser programmes, each of which approves publishers separately. Advertisers favour a relevant niche, an engaged audience or specialist expertise, for example in Google Shopping. Once approved, the surest way to win higher commission or exclusive codes is to prove incremental results.

Get paid and stay compliant

Check validation periods and payment thresholds before you commit, especially if you plan to reinvest earnings. Test your links regularly, label affiliate content clearly under the CAP Code, and run any email marketing in line with PECR and UK GDPR. Our guide to maximising website revenue through affiliate marketing goes further, or talk to EngageMore if you're building a publishing business.

What keeps advertiser and publisher relationships working

Affiliate relationships last only as long as both sides see value. Advertisers judge publishers on return, new customer share, responsiveness and the cost of extra exposure. Publishers compare conversion rates and earnings per click, and expect timely creative, offers and payments. Advertisers that offer better incentives than competitors win priority, which makes relationship management a growth lever rather than an admin task.

EngageMore's view

For a UK business new to affiliate marketing, the commission rate attracts the most attention and matters least at launch. What decides whether the channel adds profit is the plumbing underneath it. That means server-to-server tracking with a tested consent set-up, written terms on brand bidding and voucher codes. It also means validation that strips out returns and sales you'd have made anyway.

Get those foundations in place before recruiting your first publisher, and commission becomes a lever you can pull with confidence. Skip them, and you risk paying for sales you already owned while your best partners lose faith in your tracking. If you'd like an honest view of whether the channel fits your business, book a free growth audit.