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Infrastructure: Cost Benefit Analysis

Asked by Callum AndersonLabourTreasuryTabled Answered 12 January 2026UIN 102216

The question

To ask the Chancellor of the Exchequer, what analysis her Department has undertaken on the potential fiscal implications for future public spending decisions of altering the declining discount rate regime.

Answered by James Murray

The independent review of the Green Book discount rate will be published in the summer 2026.

Changes to the Green Book discount rate methodology will affect the appraisal of major infrastructure projects that involve benefits and costs well into the future.

The discount rate review will inform the government’s decisions on major projects at the next Spending Review. It will help to ensure that the government makes fair assessments of transformational projects that provide long-term benefits.

HM Treasury’s terms of reference for the discount rate review note that the lead authors should look at international comparisons to better inform their judgements on the UK approach.

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