The Australian Competition and Consumer Commission (ACCC) has published guidance urging businesses making voluntary emissions claims to use credible, science-based accounting, disclose their reliance on purchased credits and consider how average consumers would interpret their marketing. The guidance focuses on helping consumers distinguish direct emissions reductions from credits purchased from projects elsewhere. False or misleading environmental claims risk breaching the Australian Consumer Law. Emissions claims should rest on complete, reputable and clear accounting, avoid double counting and not be highly selective, broad or nonspecific. Marketing should distinguish a business’s own efforts from broader changes available to all and from legal obligations. Claims about future outcomes require reasonable grounds. Carbon credits and other certificates can complement direct emissions reductions, but businesses need a reasonable basis for marketing that implies activities are equivalent or neutralise or cancel each other out. The guidance builds on the ACCC’s 2023 general environmental claims guidance. Businesses are encouraged to review existing consumer claims and, where concerns arise, revise their messaging, strengthen supporting evidence or reconsider using the claims. Greenwashing remains a compliance and enforcement priority, and the ACCC will consider targeted enforcement against ongoing problematic conduct.