Green Book (HM Treasury)

Green Book (HM Treasury)
Name	Green Book (HM Treasury)
Publisher	Her Majesty's Treasury
Country	United Kingdom
Language	English
Subject	Public investment appraisal
First	1960s
Latest	2020s

Green Book (HM Treasury) is the United Kingdom central guidance on appraisal and evaluation for public expenditure, used across Whitehall, devolved administrations, local government in England, and non-departmental public bodies. It provides standardized techniques for cost–benefit analysis, discounting, and risk assessment to support decisions by ministers, permanent secretaries, and accounting officers in Treasury-sponsored projects such as National Health Service capital schemes, High Speed 2, and Crossrail. The Green Book informs project appraisal alongside complementary texts like the Orange Book (HM Treasury), Magenta Book, and Blue Book.

Overview and Purpose

The Green Book sets out the mandatory framework for appraising public investments for entities including HM Treasury, Department for Transport, Department for Education, Ministry of Defence, and Foreign, Commonwealth and Development Office. It prescribes economic appraisal methods used for proposals affecting public finances, including cost–benefit analysis, social welfare theory, and real options analysis, to determine value for money for portfolios such as National Infrastructure Commission recommendations, Local Enterprise Partnerships projects, and National Audit Office-audited programmes. The guidance seeks to align decisions with fiscal rules originating from Parliament of the United Kingdom procedures and the Budget (United Kingdom), ensuring compliance with Public Accounts Committee scrutiny and Comptroller and Auditor General standards.

Historical Development

Green Book origins trace to post-war fiscal reforms in the Chancellor of the Exchequer offices during the 1960s and 1970s, influenced by academic work from John Maynard Keynes successors and welfare economists at institutions like London School of Economics, Oxford University, and Cambridge University. Revisions followed fiscal events including the 1976 United Kingdom sterling crisis, the 1992 Black Wednesday, and the 2008 financial crisis, prompting updates to address monetary policy shifts and public sector borrowing dynamics overseen by the Office for Budget Responsibility and Bank of England interactions. Major editions coincided with seminal policy publications from Prime Minister administrations such as those of Margaret Thatcher, Tony Blair, and Rishi Sunak, with inputs from advisory bodies including the Institute for Fiscal Studies, National Audit Office, and Chartered Institute of Public Finance and Accountancy.

Key Principles and Methodology

The Green Book emphasizes appraisal principles like additionality, counterfactuals, and distributional impacts evaluated through social discount rate frameworks similar to those used by Organisation for Economic Co-operation and Development and World Bank guidance. It prescribes techniques for monetising benefits and costs drawing on evidence from Office for National Statistics, Behavioural Insights Team findings, and Department for Work and Pensions evaluations. Methods include sensitivity analysis, probabilistic risk assessment influenced by Monte Carlo methods literature, and discounted cash flow calculations consistent with protocols in International Monetary Fund reports and academic journals such as The Economic Journal and Journal of Public Economics.

Appraisal and Evaluation Processes

Project appraisal under the Green Book requires a business case lifecycle used by Infrastructure and Projects Authority, Crown Commercial Service, and departmental investment boards like those in Ministry of Housing, Communities and Local Government. The process stages—strategic outline case, outline business case, full business case—mirror project assurance practices in Project Management Institute standards and procurement rules under European Union directives historically relevant to UK procurement law. Evaluation demands ex post assessment aligning with National Audit Office methodologies, impact evaluations compatible with What Works Network standards, and audit trails for accounting officers who report to select committees such as Treasury Select Committee.

Application and Governance

Application of the Green Book spans infrastructure programmes like HS2, Thames Tideway Tunnel, and Crossrail 2 proposals, social programmes administered by Department for Education and Department of Health and Social Care, and international development projects coordinated with Foreign, Commonwealth and Development Office. Governance mechanisms involve the Chancellor of the Exchequer, Permanent Secretary to the Treasury, Accounting Officer responsibilities codified in Managing Public Money, and oversight by bodies including the Infrastructure and Projects Authority and Public Accounts Committee. Compliance is enforced through departmental assurance, internal audit, and external review by institutions such as the National Audit Office and academic scrutiny from centres like UCL Institute for Innovation and Public Purpose.

Criticisms and Revisions

Critiques of the Green Book have emerged from commentators at the Institute for Fiscal Studies, Adam Smith Institute, and Resolution Foundation, arguing issues with assumptions about distributional weighting, treatment of uncertainty, and applicability to complex interventions studied in randomised controlled trials and systems thinking approaches. Debates raised by scholars from University of Manchester, Imperial College London, and University of Warwick have prompted revisions to guidance on discounting, inclusion of non-market valuations from Department for Environment, Food and Rural Affairs studies, and enhanced treatment of climate risks aligned with Paris Agreement commitments. Subsequent editions incorporated inputs from cross-government reviews, consultations with the What Works Network, and methodological updates reflecting standards used by European Investment Bank and Asian Development Bank.

Category:Public finance Category:United Kingdom government publications Category:Project appraisal