Question to the HM Treasury:

To ask His Majesty's Government what changes they have made to the HM Treasury Green Book in the last two years; and what was the purpose of each change.

HM Treasury concluded its review of the Green Book in June 2025. Since then, it has published a clearer, shorter Green Book, ensuring decisions are no longer based solely on single metrics such as benefit-cost ratios (BCRs), but instead consider the full range of potential impacts.

HM Treasury has streamlined business case guidance, and has published the findings of an independent review into the Green Book discount rate, ensuring the government is taking a fair view of long-term investment proposals.

HM Treasury is also piloting place-based business cases (PBBCs) with four early adopter locations, working in close partnership with regional, local and devolved governments, including mayors, to test a new approach to appraisal that puts local objectives at the centre. Business cases for major projects and programmes are being published consistently, meaning the public can have confidence that every pound of taxpayers’ money is being spent on projects that deliver the best possible value.

HM Treasury has published a report on its progress in implementing the conclusions of the Green Book Review in 2025. The report can be found here: https://www.gov.uk/government/publications/green-book-review-2025-one-year-on