3 ad checks a UK media buyer should run under the CAP Code

What to take away

Why pre-launch CAP Code checks save a campaign

A campaign that breaks the CAP Code can be pulled after it has run. The Advertising Standards Authority (ASA) publishes the ruling, names the advertiser, and the ad must be changed or withdrawn. A media buying agency that checks earlier avoids the scramble.

Broadcast ads are cleared by Clearcast or Radiocentre before transmission. Non-broadcast ads, which include paid social, display, press and out-of-home, are not pre-cleared. They are checked only if someone complains or the ASA picks them up. The CAP Code applies to those ads, and the ASA can investigate after they appear.

That gap is where pre-launch checks matter. A buyer booking space across England, Scotland, Wales or Northern Ireland cannot rely on a platform's own review. Platform policies change and do not match UK advertising rules. Sorting UK codes from platform policies before a media buy is approved keeps the two sets of rules separate.

This article refers to the CAP Code, 12th edition, in force from 14 October 2019 and amended since. Sections 01, 03, 08 and 11 are the reference points.

Check one: substantiation of claims in bought media

Section 01 of the CAP Code requires that marketing communications are legal, decent, honest and truthful, and that advertisers hold evidence for claims before they are published.

The general compliance rules cover substantiation and social responsibility, so a claim in a paid slot is held to the same standard as one on the advertiser's own site.

Substantiation evidence must exist before the ad runs, not after a complaint. If an ad says a product is the fastest, the cheapest or clinically proven, the advertiser needs the test data, survey or certification to hand. A buyer does not need to be the expert on the evidence, but should confirm someone in the business holds it.

The practical step is a substantiation evidence file. For each claim, record the exact wording, the evidence that supports it, who signed it off, and the date. Keep the file with the media plan so it can be produced quickly if the ASA asks.

A claim that cannot be evidenced should be softened or removed before the buy is confirmed.

Some claims need a higher bar. Health, beauty and food claims often rely on trials or regulatory approvals. Financial claims fall under Financial Conduct Authority rules as well as the CAP Code. Environmental claims are covered later and have their own expectations. In each case the evidence must be current and must cover the exact claim made.

A media buying agency should build the evidence check into its ad approval route. The person who signs off the media plan should see confirmation that evidence exists. These are the ad checks that stop a booking going live on a claim nobody can defend.

Worked example: an ad claims a product is clinically proven. If the advertiser cannot produce the trial data before booking, the claim should be removed. If the ad runs without it, the ASA can publish a ruling that names the advertiser, and the ad must be pulled.

Check two: misleadingness in copy and context

Section 03 of the CAP Code deals with misleading advertising. An ad misleads if it, or its presentation, causes the average consumer to take a different decision. That includes what the ad says, what it omits and how it looks.

The misleadingness rules relevant to claims in bought media are broad, and they apply to the whole impression the ad creates.

The misleadingness test has three parts. First, what does the ad claim or imply? Second, what does the average consumer understand from it? Third, would that understanding affect their choice? A price claim, a comparison or a qualification can all change the answer.

The test is applied to the ad as it appears in the slot, not as it reads in a script.

Context matters. A small print disclaimer at the bottom of a display ad may not be seen. A headline claim in a social feed may be read without the landing page. A price that excludes a mandatory fee can mislead even if the fee is disclosed later.

Buyers should check the ad in the format and placement it will actually run.

Comparisons need care. A comparison with an identifiable competitor must compare like with like and must not discredit the other product. A claim to be cheaper than a named rival needs current price evidence. A claim to be the best in a category needs a basis that a reasonable reader would accept.

Availability claims also mislead. If an ad promotes a product at a price but stock is limited, the ad should say so. If a promotion is subject to conditions, those conditions should be clear before purchase. The CAP Code expects qualifications to be prominent enough to be seen.

A practical way to apply the test is to read the ad as a stranger would, with no knowledge of the product. Note what it promises, what it leaves out, and whether the missing information changes the decision. If it does, the ad needs a fix before the media is booked.

Worked example: for illustration, a display ad headlines a price of £10 but a mandatory £2 booking fee appears only in small print. The ASA is likely to treat that as misleading, so the buyer should change the creative or the price before media is booked.

Check three: promotional marketing and prize draws

Section 08 of the CAP Code covers promotional marketing. It applies to sales promotions, prize draws, competitions and free offers run through media channels. The promotional marketing rules require that promotions are conducted fairly and that participants can understand the terms.

A promotion run in paid media must state the significant conditions. That includes the closing date, how to enter, any age or location limits, and what the prize is. If a purchase is required, that must be clear. If the promoter can change the prize, that must be clear too.

The ASA has ruled against promotions where key conditions were buried or absent.

Prize draws and competitions have specific expectations. A prize draw must not require a purchase unless it is a lawful lottery, and free entry routes must be genuine. A competition judged on skill must have a clear judging basis. The promoter must be able to show that prizes were awarded as described.

Steps for a compliant promotion:

Promotions also fall under the CAP Code's general rules on administration. The ASA expects promoters to honour the terms, to deal with entries fairly and to avoid causing disappointment through unclear wording. A buyer should confirm the promoter has the operational capacity to run the promotion before booking media support.

Worked example: a prize draw says no purchase necessary but the free entry route is hidden. If the ASA rules, it publishes the ruling, names the promoter, and the promotion must change or stop.

Environmental claims and paid-for content disclosure

Environmental claims are a growing source of ASA rulings. Terms such as carbon neutral, net zero, eco-friendly and sustainable must be substantiated and must be clear about what they cover. A claim that a product is carbon neutral should say whether that covers the product, the packaging or the delivery, and whether it relies on offsets.

Section 11 of the CAP Code covers environmental claims. It requires that claims are based on a full life-cycle assessment where relevant, and that they do not exaggerate the environmental benefit. A claim that a product is greener than another needs evidence for the comparison.

A general claim that a company is sustainable may mislead if it only covers part of the business.

Paid-for content must be identifiable as advertising. If a brand pays an influencer or publisher to promote a product, the ad must be obviously identifiable. Labels such as ad, advert or paid partnership should be clear and upfront. A buyer placing paid content should confirm the disclosure is in the creative and not left to the platform's own tools.

Environmental claims and paid-for content both rely on evidence. For green claims, keep the assessment, the data and the scope. For paid content, keep the contract and the disclosure wording. Both should be in the evidence file before media is booked.

Evidence to keep on file before booking media

The evidence file is the buyer's defence if a complaint arrives. It should be complete before the first ad runs, and it should be easy to find. The list below covers the core items.

Evidence does not need to be perfect, but it must exist and must match the claim. If the ASA asks, the advertiser should be able to produce it quickly. A media buying agency that keeps the file with the media plan avoids a last-minute search. Keeping it with the ad approval record makes the whole route inspectable.

Using Copy Advice and ASA rulings as references

The ASA runs a Copy Advice service for non-broadcast ads. It gives a confidential opinion on whether a proposed ad is likely to break the CAP Code. The service is free, non-binding and covers non-broadcast ads only. A buyer can use it before booking media, especially for novel claims or promotions.

It can flag issues that a buyer might miss, and it is best used early, when there is still time to change the creative.

ASA rulings show how the CAP Code is applied in practice. They are published and searchable, and they name the advertiser and the ad. A buyer can cite a ruling to show why a claim needs changing. Rulings are useful for training and for building internal guidance.

When a ruling is relevant, keep a note of it with the evidence file. It shows the reasoning behind a decision. It also helps if the same issue comes up again. Over time, a library of rulings becomes a practical reference for the team.

Both Copy Advice and rulings sit alongside the CAP Code sections. The Code sets the rules, the rulings show them applied, and Copy Advice gives a view before publication. Together they reduce the risk of a campaign being pulled after it has run.

Common questions