Sizewell C could cost taxpayers £48bn, MPs call it a 'terrible deal'

Sizewell C could cost almost £48bn, with UK bill payers on the hook for an extra £9.8bn before 2040 and a further £12bn over the plant's 60-year operating life. That is the warning from the public accounts committee (PAC), the government's spending watchdog, which has branded the funding plan for the Suffolk nuclear plant a "terrible deal" for the UK taxpayer over the rest of the century.

The numbers matter because of who carries the risk. The UK government holds a 44.9% stake in Sizewell C, paid for through taxes and energy bills, after agreeing to take a near-45% share of the project. French state nuclear developer EDF holds 12.5%, British Gas owner Centrica holds 15%, Canadian investment group La Caisse holds 20%, and investment manager Amber Infrastructure holds 7.6%.

How did the taxpayer end up with the biggest stake?

The government was forced into a larger-than-expected share after buying out Chinese state nuclear developer CGN. CGN had been allowed to hold a 20% stake in Sizewell C before national security concerns emerged, and the buyout left Whitehall holding the largest position in the project.

The asymmetry is what drew the PAC's fire. While the British public could be called on to shoulder multibillion-pound cost overruns, the project's private investors would only need to put in an extra £30m, according to the watchdog.

Sir Geoffrey Clifton-Brown, the PAC chair, said: "The high level of risk borne by taxpayers and consumers for the construction of Sizewell C is extraordinary. Private investors look set for significant returns on their investments, while customers are likely to be saddled with higher energy bills."

He urged the government to "focus on the successful delivery of this project" and on building confidence in the UK's nuclear industry more broadly, so that taxpayers will "never be put in this position again".

What does this change for energy consumers and the project's future?

For households, the exposure runs through both taxes and energy bills across the rest of the century. The government expects Sizewell C to cost between £40.5bn and £47.7bn, with construction completing between 2039 and 2043 — a timeline that makes the plant a successor to the heavily delayed Hinkley Point C in Somerset.

The committee has demanded the scenario analysis underpinning those cost estimates within the next three months. It also wants ministers to report on the project's development every six months to keep track of progress.

Critics went further. Alison Downes of the Stop Sizewell C campaign group and Prof Steve Thomas of Greenwich Business School, who provided joint evidence to the committee, argued that abandoning the project today would cost less than paying inflated energy bills over 60 years "multiple times over".

They called on the government to rule out using this funding model for future nuclear projects. "All it offers is a free ride for investors and financial pain for households," they said in a joint statement.

What does the government say?

A government spokesperson said the PAC report "completely ignores that investors are incentivised to complete construction as cheaply and quickly as possible" through the terms of the deal.

"Once operational, Sizewell C could save £2bn a year across the energy system, cutting costs for families up and down the country, and the project is already making good progress with over 2,000 workers on site," the spokesperson added.

Industry voices backed that case. Tom Greatrex, chief executive of the Nuclear Industry Association, said Sizewell C would provide "clean, reliable and constantly available power" that could save households billions from paying the cost of balancing the grid or building extra network connections.

"Currently, the consumer is footing a bill of £2.8bn so far this year to manage a dysfunctional grid, paying both for wind to stop generating at some times, and for gas-powered backup at others," he said.

The immediate test is procedural: whether ministers hand over the cost scenarios within three months, and whether the six-monthly reporting the PAC wants becomes the mechanism that keeps a near-£48bn project honest.