The Prime Minister announced changes on 22 October 2026 to the Green Book, the official framework used to assess business cases for UK spending projects, according to HM Treasury and the Prime Minister's Office. Under current rules, projects such as housing schemes or transport proposals are considered independently, which the government says can undervalue the wider potential of a place.

The updated guidance is intended to help local and strategic authorities build investment plans around a fuller picture of their local economy, identifying barriers to growth and coordinating investment around them. New place-based business cases would weigh a place's growth potential and ensure previously overlooked areas are properly considered. No10 North will support local areas, including those without mayors, to engage with the new process and draft strong business cases.

The changes were announced alongside a meeting with English mayors at No10 North. The government said further Green Book reforms will come at next week's Budget, alongside a roadmap for future fiscal devolution giving regional leaders control over how they allocate a share of some national taxes. Chancellor John Healey said last month's changes included cutting the headline discount rate from 3.5% to 3%.