Bill payers pay £727 for every £1 investors put into Britain’s new nuclear plant
Key Points
- MPs called the Sizewell C deal a terrible deal for UK taxpayers
- Overruns could cost bill payers £21.8 billion more and investors £30 million
- Investor returns stay above 10% even at the upper cost estimate
- Bill payers have funded the plant through energy bills since November 2025
- Taxpayers cover any decommissioning shortfall after the plant closes
The Public Accounts Committee said UK bill payers face £21.8 billion in extra costs if Sizewell C overruns, while investors add £30 million.
The committee of MPs published its report on the Suffolk nuclear power station on Wednesday (28 October). “Sizewell C represents a terrible deal for the UK taxpayer,” said the Public Accounts Committee.
Sizewell C will cost between £40.5 billion and £47.7 billion to build, and the government expects it to be fully operational in 2039. The plant will run for at least 60 years and produce enough electricity for six million homes.
Bill payers started funding Sizewell C through their energy bills in November 2025, years before it generates any power. They will pay £24.7 billion during construction and a further £111.8 billion once the plant starts operating.
If construction costs rise to the top of the estimate, bill payers would pay £9.8 billion more during construction and another £12 billion over the plant’s operating life. Private investors would only have to put in an extra £30 million in cash.
The committee calculated that this works out at roughly £727 from bill payers for every £1 of extra cash from investors. Bill payers would cover the higher construction bill as well as the cost of extra borrowing and longer payouts to shareholders.
Private investors expect annual returns of 12% to 13% if the project stays on budget. Even if costs hit the upper estimate, those returns only fall to between 10.8% and 11.4%.
“This all breaks the rule that financial returns be proportionate to the risk and raises concerns about whether investor incentives are sufficiently aligned with delivery performance,” said the committee.
Private investors own 55.1% of Sizewell C Ltd, with the government holding the remaining 44.9%. The government still provides most of the money, including £36.6 billion in loans through the National Wealth Fund.
The government has agreed to pay up to £70 billion if the plant shuts down permanently through no fault of Sizewell C Ltd. It has also offered a loan facility of up to £8 billion if the company runs short of cash.
Bill payers will fund a pot of between £5.1 billion and £5.8 billion over the plant’s lifetime to cover decommissioning. If that pot falls short after the plant stops running, taxpayers will cover the difference.
Every plant using the same reactor design has run late, over budget or both. Flamanville 3 in France is around 14 years behind schedule, and Olkiluoto 3 in Finland finished 14 years late and 320% over budget.
Hinkley Point C in Somerset, which uses the same design, is currently five to seven years late. The project is also running around 100% over its original budget.
The Department for Energy Security and Net Zero told the committee these were the best terms available in the current market. It said private investors would bring stronger project management to Sizewell C.
The committee wants Sizewell C Ltd and the department to report to Parliament every six months, including the expected impact on consumer bills. Current plans only require an annual report to Parliament, while shareholders receive updates every six months.
