Overview

• Cornwall Insight’s final forecast, following an observation window that closed on 18 August, puts the October to December 2025 default tariff cap at £1,737, about 1% higher than the current £1,720.
• Ofgem is scheduled to confirm the official cap level on 27 August.
• The consultancy assumes an expanded Warm Home Discount that would add roughly £15 to a typical annual bill while providing £150 support to around 2.7 million people.
• The update reverses Cornwall Insight’s July expectation of a small fall, with volatile market conditions cited in recent weeks.
• Analysts see a potential small drop in January, contingent on geopolitics, weather, policy costs and possible new charges such as support for nuclear investment.