Can You Call Your Business 'The Best' in an Ad? UK Rules on Claims Explained

By the Oski Marketing team · Updated 5 October 2026 · 6 min read

You can use obvious, unmeasurable praise like "the friendliest salon in Walthamstow", because the CAP Code allows puffery nobody takes literally. But "the best", "No.1", "leading" and "cheapest" are usually read as objective comparisons, so you need documentary evidence covering every competitor before the ad runs. Reviews alone do not count as proof.

This is a general guide, not legal advice. It summarises ASA and CAP guidance, linked throughout, at the time of writing.

What is the difference between puffery and an objective claim?

Puffery is exaggeration that consumers will not take literally; an objective claim is one people could measure or check. The ASA's guide to objective vs subjective claims says the Code expressly permits puffery, but that puffery cannot hide an objective claim. If a statement could reasonably be read as factual, you need evidence.

Rule 3.7 of the CAP Code says marketers must hold documentary evidence to prove claims that consumers are likely to regard as objective. The key word is "likely": it is how a reasonable customer reads your ad that counts, not what you meant.

Context matters too. The ASA's superlative claims advice notes that "the best" is generally treated as an objective comparison against all competitors, and that an advertiser's intention to use something as puffery does not stop the ASA reading it as a factual claim.

Can you say "the best"?

Sometimes, depending on what "best" is attached to. The ASA's guidance explains that "best" tied to a measurable criterion is objective, while "best" about look, taste or feel is more likely to be subjective. Here is how common local business phrases tend to sit:

If you cannot produce the evidence, change the words. "We think it's the best flat white in Peckham. Come and judge for yourself." reads as opinion. "The best café in Peckham" reads as a fact.

What about "No.1", "top-rated" and "leading"?

These are almost always treated as objective. The ASA's No.1 claims guidance says unqualified "number 1" claims are usually read as "best-selling" and need comparative evidence on unit sales, market share or both. Absolute claims are understood as comparisons with the entire market.

Qualified claims can work if they are accurate and checkable. The same guidance gives the example of a rating claim tied to a named review platform, which may be read in that context rather than as best-selling. If you use something like "highest-rated electrician in Enfield on [platform]", you need to:

1. Be able to show it was true when the ad ran, with a dated screenshot of the comparison.
2. Make the basis clear in the ad so people can check it.
3. Update or remove it as soon as it stops being true.

"Top-rated" and "award-winning" follow the same logic: say which rating or award, from whom, and when.

Can you say "guaranteed"?

Yes, for a real guarantee with clear terms, but not to suggest a result is certain when it is not. The ASA's guarantees guidance says significant limitations must be stated clearly (rule 3.56), the word must not confuse consumers about their legal rights (rule 3.55), and money-back guarantees must be honoured promptly (rule 3.57). It also gives an example of a broadband provider found in breach for a "fastest WiFi Guarantee" that did not actually guarantee the fastest speeds.

For a small business:

• Fine: "12-month workmanship guarantee on every installation. Excludes accidental damage."
• Risky: "Guaranteed to fix any leak first time."
• Avoid: promising more customers, a top Google position or any other outcome you do not control.

Can customer reviews be used as proof?

No. The ASA's article on opinions in advertising says you cannot use a testimonial to make a claim you could not otherwise make, and that testimonials alone do not constitute substantiation. A review saying "best builder in Bromley" is that customer's opinion. Put it in your ad as a headline and it becomes your claim.

What you can do is quote genuine reviews accurately, attributed to the customer, with their permission. Rule 3.45 adds that you must make clear where reviews have been incentivised.

Reviews are also covered by consumer law. Under the Digital Markets, Competition and Consumers Act 2024, the CMA says the new regime that came into force in April 2025 includes an explicit ban on posting and commissioning fake reviews, and the CMA can fine up to 10% of global turnover for consumer law breaches. Collect reviews honestly; our guide to getting more Google reviews shows how.

What wording is safer?

Specific, true and checkable wording usually sells better than superlatives anyway, because customers have seen "the best" a thousand times. Swap like this:

• "The best plumber in Croydon" becomes "Gas Safe registered, based in Croydon, answering calls until 8pm."
• "No.1 for customer service" becomes a real, named customer review quoted with permission.
• "Cheapest in London" becomes "Fixed price: £X for a standard boiler service, VAT included", with your real price.
• A promised outcome becomes "Here is exactly what we will do, and what we will do if it goes wrong."

For more on writing a homepage that turns visitors into calls without overclaiming, see homepage copy that gets calls. The wider rules are in our CAP Code guide.

What to do this week

• Search your website, Google profile and social bios for "best", "No.1", "leading", "top", "cheapest" and "guaranteed".
• For each one, either find dated evidence or rewrite it as a specific fact or an obvious opinion.
• Replace one superlative headline with a genuine customer quote, used with permission.
• Check any guarantee has its main conditions written right next to it.
• If you are unsure about a claim in a paid ad, send it to the free ASA Copy Advice service first.

At Oski Marketing we never describe ourselves as "the best" in our own marketing for the same reason, and we apply the same checks to client ads.