Britain’s Lower Project Hurdle Seeks to Unlock Long-Term Infrastructure Capital

London, 5 September 2026 – Britain is preparing to lower a key hurdle used to assess public investment, a technical change that could materially improve the case for long-duration infrastructure projects. The Treasury plans to reduce the Green Book social discount rate from 3.5% to 3%, giving greater present value to benefits that emerge over decades from transport, housing, health and other public assets.

The adjustment may appear modest, but discount rates have a powerful effect on project appraisal. A higher rate reduces the value assigned today to future economic and social benefits, making capital-intensive schemes with long payback periods harder to justify. Cutting the rate should allow more of those benefits to enter official calculations and may help projects that previously struggled to pass value-for-money tests.