UK Government updates Green Book to embed environmental principles in spending decisions

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The UK Government has updated its central appraisal guidance, The Green Book: appraisal and evaluation in central government, to explicitly incorporate environmental considerations, including the Environmental Principles Policy Statement (EPPS) and duties under the Environment Act 2021.

The Green Book, published by HM Treasury, is the UK Government’s core guidance on appraisal, i.e. the process of assessing the costs, benefits and risks of alternative options for achieving government objectives. It provides a structured framework to help civil servants and decision-makers choose the most effective and efficient ways to use public resources, informing policies, programmes and projects that involve significant public spending.

What’s changed and why it matters

The revised Green Book, updated in early February 2026, now reflects a range of government commitments to embed environmental policy into spending decisions. Amongst the changes:

  • It formally integrates the Environmental Principles Policy Statement, making it clear that environmental principles such as integration, prevention of harm, precaution, rectification at source and polluter pays should be considered as part of appraisal processes where relevant.
  • Appraisal guidance now requires greater consideration of climate and biodiversity outcomes, and legally binding environmental targets set under the Environment Act 2021 and subsequent environmental improvement frameworks.

The inclusion of environmental principles into the UK’s central spending guidance marks a shift toward ensuring that environmental outcomes are treated as an integral part of policy and investment appraisal, and not an afterthought.

Environmental Principles Policy Statement

The Environmental Principles Policy Statement (EPPS) sets out five internationally recognised principles that are designed to guide decision-makers towards better environmental protection and sustainable outcomes:

  • Integration: environmental protection should be considered across policy areas
  • Prevention: avoid environmental damage before it occurs
  • Precaution: act cautiously where there is uncertainty
  • Rectification at source: tackle environmental harm at its origin
  • Polluter pays: those responsible should bear the cost of damage

These principles stem from the Environment Act 2021, which requires ministers to have due regard to the EPPS when making policies. Embedding them in the Green Book means they now influence how government analyses and compares options for public expenditure as well as regulatory and tax interventions.

Reaction from environment bodies

The Office for Environmental Protection (OEP) has welcomed the move, describing the inclusion of the EPPS and biodiversity duties in the Green Book as a positive step towards embedding environmental considerations across government decision-making. The OEP highlights that this change reinforces a legal duty on ministers and helps align economic appraisal with the UK’s environmental goals.

What this means for ecologists and environmental managers

For CIEEM members and other environmental professionals, the updated Green Book presents both:

  • An opportunity: strengthened policy-making and investment decisions that better account for environmental risks and benefits, particularly for climate resilience and biodiversity outcomes.
  • A challenge: ensuring that environmental considerations are sufficiently evidenced, quantified where possible, and robustly integrated into appraisal practices used across government departments.

Environmental professionals advising clients on bids, business cases or policy submissions to central government will need to ensure that robust environmental information and analysis is included early in appraisal and business-case processes to align with the updated guidance.

Further evidence for nature’s central importance

Further to other landmark evidence – including the Dasgupta Review on the Economics of Biodiversity, the recent national security assessment highlighting biodiversity loss as a systemic risk, and the scientific conclusions from IPBES-12 – the formal embedding of environmental considerations within the Green Book must become more than a technical amendment.

It should be used as a central, strategic lever to reinforce the urgency of nature recovery across government. Together, these publications provide an increasingly coherent and strategic narrative that biodiversity loss is not a niche environmental issue but an economic, fiscal and security risk that undermines long-term prosperity and stability.

The environmental sector now needs to consistently reference this body of evidence in policy activities and engagement, ensuring that ministers and civil servants cannot ignore the economic case for nature recovery.

By aligning advocacy with Treasury language – natural capital, risk management, resilience, long-term value for money – and by demonstrating how nature-positive investment supports national security and economic stability, we can help shift nature recovery from the margins of government policy to the heart of economic decision-making.