Comparative advertising is any advertising that names, shows or clearly identifies a competitor or its products, so that the audience weighs your offer against theirs. In the UK it is lawful, provided the comparison is fair, accurate and something you can prove.
How comparative advertising works
The rules come from two places. The Business Protection from Misleading Marketing Regulations 2008 set the legal conditions a comparison has to meet, and the comparison rules in section 3 of the CAP Code apply the same principles to non-broadcast marketing: search ads, social posts, emails, landing pages and your own website. The Advertising Standards Authority deals with complaints about the ads, Trading Standards can enforce the regulations, and a competitor can separately go to court if it believes you have misused its trade mark.
In practice, a comparison stays on the right side of the line when it:
- compares products that meet the same need or serve the same purpose, such as two bookkeeping apps for sole traders, not a bookkeeper and a spreadsheet template;
- compares features that are material, relevant, verifiable and representative, and price can be one of them;
- does not mislead through what it says or what it leaves out;
- does not denigrate the competitor, create confusion between the two businesses, or ride on the competitor’s trade mark or reputation;
- does not present your product as an imitation or replica of a branded one.
Verifiable is the word that trips people up. If you say you are cheaper, the reader must be able to check the comparison, so the ad or the page it leads to should say what was compared, on what date and on which terms. The evidence also has to exist before the ad runs, which is the point of substantiation.
Online, comparative advertising usually takes one of three forms: search ads that appear for a rival’s brand name as part of a competitor campaign, “X vs Y” pages written for comparison keywords, and comparison tables on pricing or product pages.
Why it matters for a UK business
A comparison is persuasive because it does part of the buyer’s research for them. Someone searching for two named accounting packages side by side, or for a rival electrician by name, is close to a decision, and a clear, honest comparison can win it. The same qualities make it risky. Complaints about comparative claims are often made by the competitor, who knows its own prices and features better than you do and has every reason to object. ASA rulings are published with the advertiser named, and you will be told the ad must not appear again in its current form.
Comparisons also date faster than almost any other copy. A competitor cuts a price or adds a feature, and a claim that was true in March is misleading by June. For that reason I treat every comparison page as something with an owner and a review date, never a page that is published and forgotten.
Common mistakes
- Claiming to be “the cheapest” or “the best value” without a dated, like-for-like price check you could send to the ASA.
- Comparing your top plan with a competitor’s entry plan, or your sale price with their standard price.
- Using a competitor’s brand name in ad text in a way that suggests you are them or are connected to them.
- Mocking the competitor instead of comparing facts.
- Choosing only the features you win on while implying the comparison is complete.
- Leaving a comparison table live long after the competitor’s offer has changed.
How to act on it
Before writing a comparative claim, note exactly which features you are comparing, where the competitor’s information came from and the date you checked it. Save screenshots or PDFs of their pricing page. Compare like with like: the same plan level, the same quantity, the same delivery terms, and prices shown on the same VAT basis on both sides.
On the page or in the ad, say what the comparison rests on, for example “Prices checked on 1 October 2026 for the standard monthly plan”. Keep the tone factual and let the facts do the persuading. Then put a review date in the diary, monthly for prices and quarterly for features, and update or remove the claim when the facts move.
If you bid on competitor brand terms, keep their name out of your ad text unless you are making a fair, checkable comparison, and send the clicks to a page that explains the difference honestly. My Google search ads management runs competitor campaigns this way, with any comparison page checked against these rules before it goes live.