Written question asked by Sarah Olney (Liberal Democrat) on Friday, 28 August 2026, in the House of Commons. It was due for an answer on Wednesday, 2 September 2026. It was answered by Emma Reynolds (Labour) on Wednesday, 9 September 2026 on behalf of the Treasury.

Infrastructure

Question: To ask the Chancellor of the Exchequer, what his Department's policy is on providing support for infrastructure projects that have a negative net present value in their appraisals.

Answer

The Government published a new version of the Green Book in February. This ensures that government decisions are no longer based solely on single metrics, such as benefit-cost ratios or net present social values. They must instead take into account the full range of economic and social impacts that arise from the project.

The new Green Book makes clear that a proposal with a benefit-cost ratio of less than one (i.e. a negative net present social value) may still represent value for money. This may be the case, for instance, if the project has significant benefits that cannot be expressed in monetary terms and which therefore cannot be included in a benefit-cost ratio.

Secondary information

Type: Written question
Reference: 21300
Session: 2026-27
Subjects: Infrastructure Government assistance
Link: View this Written question on www.parliament.uk

Infrastructure

Secondary information

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