UK advertisers tend to treat the CAP Code and the Advertising Standards Authority as a formality until the first time a winning ad is pulled mid-flight. It is self-regulation, but the ASA works with the platforms, and the practical effect of a ruling is that your advert stops running and the reasoning is published under your name.
Under the CAP Code, substantiation comes first
The principle most often missed: under the CAP Code, you are expected to hold evidence for a claim before it runs. Not to produce it when challenged. "We can back that up if anyone asks" is not the standard.
In practice that means someone has to hold the file. If your ad says customers save an average of forty percent, there needs to be a document showing how that average was calculated, over what period, from what sample.
The claims that generate rulings
- "Up to" figures. If you advertise savings of up to fifty percent, a meaningful proportion of customers should achieve something near that. One customer out of a thousand is not enough.
- Best, cheapest, number one. Comparative superlatives need evidence covering the market you implied, not a selective comparison.
- Before and after imagery. Heavily scrutinised in health, fitness and cosmetics. Lighting, posture and time gaps all matter.
- Testimonials. Must be genuine, held on file, and typical — or clearly labelled as atypical.
- Urgency and scarcity. A countdown timer that resets, or "only three left" that is always three, is straightforwardly misleading.
- Prices that are not the price. Mandatory fees revealed late is both an ASA matter and a consumer protection one.
What it means for how we build accounts
Three practical changes:
Claims get reviewed at brief stage. It costs nothing to question a headline before production. It costs a shoot and a fortnight to question it after.
We keep a claims file per client. Every quantified claim in live creative, with its source and the date it was verified. When something is challenged — or when a new buyer joins the account — the evidence is in one place.
Landing pages are part of the advert. This is the one clients find most surprising. A compliant ad pointing at a page making a stronger claim does not protect you. The journey is assessed as a whole.
The useful instinct: if you would be uncomfortable explaining how you arrived at a number, do not put it in the ad.
Regulated categories need more than this
Finance, health and anything involving claims about outcomes carry additional obligations beyond the CAP Code. We will flag what we can see, and your own compliance sign-off still has to happen before anything runs. We build the accounts; we are not your compliance function, and an agency that claims to be is overreaching.
Why this is actually an advantage
Every competitor faces the same code. Plenty of them write loose claims anyway, and some of them get pulled. An advertiser who builds on claims that can be substantiated does not have a weaker proposition — they have one that survives, which over a year is worth considerably more than a headline that performed brilliantly for three weeks.
It also tends to produce better advertising. "Save up to 50%" is a weaker line than a specific, verifiable, slightly smaller number with a real customer attached to it.
More on how we handle UK accounts on the UK page.
Questions people ask
What is the CAP Code?
It is the UK advertising rulebook written by the Committee of Advertising Practice and enforced by the Advertising Standards Authority. It covers non-broadcast advertising, including paid social and search, and applies to the advertiser rather than to the agency that placed the ad.
Is the ASA able to fine me?
It cannot issue fines directly. It can order an ad withdrawn, publish a ruling naming you, have platforms refuse your ads, and refer persistent cases to Trading Standards or the regulator for your sector. The published ruling is usually the part that costs the most.
What counts as substantiation?
Documentary evidence held before the claim runs, strong enough that an independent reader would reach the same conclusion. For a performance claim that means the underlying data; for a superiority claim it means a fair comparison on a like-for-like basis.
Which claims draw rulings most often?
Pricing that omits mandatory costs, testimonials presented as typical results, superiority claims with no comparison behind them, and urgency that is not real. Health, finance and gambling claims attract extra rules on top of the general ones.