In 2025, the UK’s Competition and Markets Authority (CMA) gained significantly stronger powers to tackle greenwashing, with a new mandate allowing it to impose fines on companies found in breach. With new powers to directly enforce consumer protection law and issue significant financial penalties for misleading environmental claims, observers can expect a stricter crackdown on greenwashing this year. This shift has had a defining influence on how organisations approach green marketing in 2026, particularly as the current business environment faces heightened scrutiny, legal accountability and far lower tolerance for vague or unsubstantiated claims. Sustainability marketing will be increasingly shaped by evidence, governance and transparency, forcing brands to rethink how they approach their green marketing strategy.
Ensuring Credible Green Marketing Through Regulations
Regulatory Guidance in the UK
The UK Green Claims Code sets out clear principles for making environmental claims that are truthful, clear and supported by evidence. Since its introduction in 2025, the green claims code has given the CMA the authority to regulate sustainability claims made by organisations. As of 2025,the CMA can now issue fines of up to 10% of a company’s global turnover if they are caught issuing misleading environmental claims. In early 2026, UK government guidance also reinforced the expectation that green claims must be accurate across the supply chain and read alongside the Green Claims Code.
Learn More: Understanding the Green Claims Code | Tunley Environmental
UK Financial Services: The FCA’s Anti-greenwashing Rule
In the UK finance and investment industry, the Financial Conduct Authority (FCA) has published finalised guidance on its anti-greenwashing rule, under the Sustainability Disclosure Requirements (SDR)package. Multiple summaries of the FCA position note that the anti-greenwashing rule applies to all FCA-authorised firms and came into effect on 31stMay 2024, requiring sustainability-related claims to be clear, fair and not misleading.
Regulatory Guidance in Europe
The EU’s approach has been politically dynamic, with public reporting showing uncertainty around the proposed Green Claims Directive. However, organisations selling into the EU cannot treat this as a “pause” on compliance. Wider EU consumer rules on environmental claims continue to tighten, and several legal and policy briefings point to enforcement dates in 2026 for EU anti-greenwashing measures. Additionally, several member states have national laws that seek to enforce anti-greenwashing mandates.
What Credible Green Marketing in 2026 Entails
Many organisations still treat credibility as a tone of voice: cautious language, softer claims, fewer absolutes etc. Those measures alone will not hold up for ensuring green marketing in 2026 as credibility becomes increasingly defined by whether a claim can survive direct challenges from consumers, investors and other stakeholders.
A practical definition of credible green marketing typically includes:
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Evidence-led claims: backed by data, tests, analyses, third-party assessments or studies that can be produced on request.
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Clarity and specificity: plain-English explanations, boundaries and assumptions made explicit.
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Lifecycle thinking: claims reflect the full lifecycle impact, not just a convenient stage.
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Consistency across channels: the website, sales deck, packaging and annual report do not contradict each other.
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Governance: someone is accountable for approvals, substantiation and version control.
Our Green Claims Code Guide frames green marketing as something that must be compliant, measurable and credible, with a clear emphasis on avoiding greenwashing and aligning claims with verified metrics. That framing aligns closely with how regulators interpret green claims risk.
How Greenwashing Often Happens in Practice
“Greenwashing” is often imagined as deliberate deception, and while that might be the case in some situations, most risks in reality come from weak processes, unclear ownership and oversimplification.
Typical causes of greenwashing risk:
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Vague language: terms like “eco-friendly”, “green”, “sustainable” or “planet positive” used without definition or quantification.
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Selective disclosure: promoting one improvement while ignoring a larger negative impact in the same product line.
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Implied zero impact: marketing suggests “no emissions” or “no harm” where the reality is “lower impact than before”.
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Inappropriate comparisons: “50% less carbon” without explaining the baseline, scope, or method.
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Over-reliance on offsets: claims that imply equivalence between reductions and compensated emissions without clear context.
Real-world rulings show how narrow the margin for error has become. For example, in 2024,the UK’s Advertising Standards Authority (ASA) banned a Virgin Atlantic advert for implying a flight was “100% sustainable” due to the way consumers could interpret the environmental impact of sustainable aviation fuel.
A Step-by-Step Guidance to Building Trust Through Credible Green Marketing in 2026
1. Start with verifiable data, not creative concepts
Credible green claims are built on measurable performance. That might include:
- Energy use and renewable energy procurement data
- Water consumption and water stress context
- Material sourcing and recycled content verification
- Emissions inventories and reduction trajectories
- Product-level lifecycle assessment outputs
The Tunley Green Claims Code guide emphasises that green marketing begins with accurate data and that sustainability managers often oversee the gathering of lifecycle metrics to ensure claims are substantiated.
Learn More: Sustainability Managers Can Support Ethical Green Marketing
Practical action in 2026:
If a claim cannot be backed with a named science-based method (for example, a lifecycle assessment boundary or a carbon accounting approach), it should be rewritten or dropped.
2. Define the claim’s boundaries so it cannot be misread
The organisations that avoid greenwashing accusations often do something simple: they specify boundaries.
Examples:
- “Pack contains 60% recycled plastic (verified by supplier chain-of-custody documentation)”
- “Scope 1 and 2 emissions reduced by 18% since 2022 baseline (market-based method)”
- “Designed for repair: spare parts available for 7 years”
This is where sustainability marketing becomes a translation exercise. Technical teams hold the data while marketing teams turn it into human language without losing accuracy.
3. Make lifecycle thinking visible
Regulators repeatedly flag the problem of “single-stage storytelling”, where a claim is technically true for one part of a product journey but misleading overall. Lifecycle credibility can be strengthened by:
- Stating which lifecycle stages are included (raw materials, manufacturing, transport, use, end-of-life)
- Explaining trade-offs (“higher recycled content increased energy use in manufacturing; net impact still reduced overall”)
- Avoiding claims that imply “no impact” unless that can be proven
- Add actual data in kgCO2e for increased factual credibility
4. Build an internal approval process that matches the risk
Credible organisations treat green claims like financial claims: reviewed, approved and documented. A workable governance model includes:
- A named owner for each claim category (product, corporate, climate, packaging)
- A substantiation file for each recurring claim (evidence, science-based data, method, dates, version history)
- A sign-off step from sustainability or compliance before publication
- Periodic re-validation (especially if suppliers or materials change)
5. Align messaging across channels and documents
A frequent trigger for scrutiny is inconsistency: the sustainability report says one thing, a product page says another and a sales deck adds a stronger claim with no evidence. Credible green marketing in sustainability reporting means translating technical data into accessible narratives while building trust through verified metrics. The practical implication is straightforward: the sustainability report, website copy and campaign assets should use the same substantiated claim language.
The Bottom Line
Succeeding with green marketing in 2026 requires an organisation to treat credibility as a system: measured performance, credible claims, consistent language and clear governance. There is also the human touch; storytelling can bridge the gap between sustainable practices and consumer participation, but it must be backed by verifiable action because misleading claims can lead to legal and reputational consequences. A critical feature of trustworthy sustainability marketing is that audiences expect transparency about limitations. When organisations show their workings, they often build more trust than those that only share polished outcomes.
Our expert sustainability scientists support organisations to communicate sustainability work credibly, align marketing with evidence and reduce greenwashing risk through compliant, data-led messaging.