ASA vs CMA: who polices green ads in the UK
Two separate UK regulators police green claims, and if your claim runs in advertising you have to satisfy both. The Advertising Standards Authority (ASA) regulates the content of ads against the CAP and BCAP Codes and rules on complaints about specific ads. The Competition and Markets Authority (CMA) enforces consumer protection law across all your marketing — not just ads — under the Green Claims Code and the Digital Markets, Competition and Consumers Act 2024, and since 6 April 2025 it can fine directly. The two overlap heavily on green claims, but clearing one does not clear the other. Only a court can decide an actual breach of the law.
The ASA: the advertising regulator
The ASA administers the UK Advertising Codes — the CAP Code (non-broadcast: online, social, print, out-of-home) and the BCAP Code (broadcast). Its focus is the content of advertisements. On environmental claims, CAP Code rule 11.1 requires that the basis of an environmental claim be clear, and warns that unqualified claims can mislead if they omit material information. The ASA acts mainly on complaints (and its own monitoring), and its sanction is a ruling that an ad is misleading and must be withdrawn or amended — reputationally significant, and backed by referral routes for persistent offenders.
The CMA: the consumer-law enforcer
The CMA is not an advertising regulator; it enforces consumer protection law across the whole of your marketing and packaging, in and out of advertising. Its Green Claims Code sets the six principles, and under the DMCCA 2024 it can now decide a business has breached consumer law and impose a fine of up to £300,000 or 10% of worldwide turnover, whichever is greater, without going to court. Its reach is broader than the ASA's (packaging, websites, in-store, product names, imagery) and its financial teeth are sharper.
General information, not legal advice. This guide explains how the ASA and the CMA each regulate green claims. It is not legal advice, and only a court can decide whether a specific claim breaches the law.
How they differ — at a glance
- What they cover: ASA — advertising content. CMA — all commercial practices, including packaging, websites, product names and imagery.
- The rulebook: ASA — the CAP/BCAP Codes. CMA — consumer protection law, interpreted through the Green Claims Code, enforced via the DMCCA.
- The sanction: ASA — a ruling to withdraw or amend an ad, with reputational impact and escalation routes. CMA — binding directions and direct fines up to 10% of global turnover.
- How a case starts: ASA — largely complaint-led and monitoring. CMA — its own investigations and sector reviews.
Why you must satisfy both
A green line in a paid ad is simultaneously an advertisement (ASA territory) and a commercial practice (CMA territory). The ASA can rule the ad misleading under the CAP Code; the CMA can treat the same claim as a breach of consumer law under the DMCCA. The regimes overlap but are legally distinct, so passing an ASA test is not a defence to the CMA, and vice versa. Both have converged on the same problem claims — vague "eco"/"sustainable" wording and unqualified "carbon neutral"/"net zero" — which is why a claim written to satisfy the Green Claims Code's six principles will usually also satisfy the CAP Code, and is the safest way to clear both at once.
The ASA on carbon-neutral and net-zero ads
The clearest area of ASA action is neutrality claims. The ASA advises against unqualified "carbon neutral" and "net zero" claims, and has upheld complaints against carbon-neutral and carbon-negative advertising that did not make clear the claim relied on offsetting — including rulings involving major brands. Where offsetting is part of the basis, the ad should say so and explain it, kept close enough to the main claim to be seen. (We describe only rulings and guidance the ASA has published.)
Frequently asked questions
What is the difference between the ASA and the CMA on green claims?
The ASA regulates advertising content against the CAP/BCAP Codes and rules on complaints about specific ads. The CMA enforces consumer protection law across all marketing (not just ads) under the Green Claims Code and the DMCCA 2024, and can fine directly since 6 April 2025. A green claim in an advert falls under both.
Do I have to satisfy both the ASA and the CMA?
If your green claim appears in advertising, yes. The ASA can rule your ad misleading, and the CMA can treat the same claim as a breach of consumer law. The regimes overlap but are separate, so clearing one does not clear the other.
What does the ASA say about carbon-neutral ads?
It advises against unqualified "carbon neutral" and "net zero" claims and has upheld complaints against carbon-neutral and carbon-negative ads that did not make the reliance on offsetting clear. Where offsetting is involved, say so and explain the basis, close to the main claim.
Sources
- ASA/CAP: environmental claims (general), CAP Code rule 11.1 — the advertising rules on environmental claims. asa.org.uk — Environmental claims: general
- ASA/CAP: carbon offsetting and carbon neutral — the guidance and rulings on carbon-neutral/net-zero ads. asa.org.uk — Carbon offsetting and carbon neutral
- CMA Green Claims Code (2021) — the six principles the CMA applies to environmental claims. gov.uk — Green Claims Code
- Digital Markets, Competition and Consumers Act 2024 — the CMA's consumer-law enforcement and direct-fine powers; in force 6 April 2025. legislation.gov.uk/ukpga/2024/13
Content current as of 9 July 2026. ASA and CMA guidance can change — re-check the primary source before acting on anything time-sensitive.
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