MPs have warned that the financing agreement for Sizewell C could leave taxpayers and electricity consumers exposed to billions of pounds in additional costs while private investors enjoy substantial protections.
In a report published on 28 October 2026, the House of Commons Public Accounts Committee (PAC) raised serious concerns about the balance of risk and reward in the deal for the proposed nuclear power station on the Suffolk coast.
Costs could reach £47.7 billion
The committee said Sizewell C has a projected cost range of £40.5 billion to £47.7 billion, with construction expected to finish between 2039 and 2043 under the scenarios it examined. The figures are forecasts and regulatory thresholds, not sums already spent.
Under the higher-cost scenario, consumers could be required to pay an additional £9.8 billion during construction and £12 billion over the plant’s 60-year operating contract through higher electricity bills. By comparison, the committee said private investors would be required to provide only an additional £30 million.
Those figures are conditional estimates of financial exposure, not an announcement that households have already been charged £21.8 billion.
Public takes significant risk without majority control
The Government holds a 44.9% equity stake in Sizewell C, while other investors hold a combined majority. The National Audit Office has reported that the Department for Energy Security and Net Zero committed up to £3.8 billion in equity and the National Wealth Fund up to £36.6 billion in loans. Loans are financing commitments rather than a direct measure of losses to taxpayers.
The project uses a regulated asset base model, under which electricity consumers help finance construction before the station begins generating power. The committee questioned whether the arrangements provide sufficient incentives for investors to control costs and whether the Government can adequately protect the public interest.
MPs demand more transparency
The committee called for progress reports every six months, including forecasts of consumer bill impacts and investor returns. It also wants greater transparency over the assumptions underpinning the project and regular reporting on funds set aside for eventual decommissioning.
Committee chair Sir Geoffrey Clifton-Brown described the public’s level of exposure as extraordinary and warned that the Government must ensure the project is delivered successfully so that similar financing terms are not necessary in future.
Government defends nuclear investment
The Government disputes the committee’s assessment, arguing that investors have incentives to deliver the project as efficiently as possible. It says Sizewell C could save around £2 billion a year across the electricity system once operational, while supporting energy security and low-carbon generation. Those savings are Government projections, not realised benefits.
The planned 3.2-gigawatt power station is expected to generate electricity equivalent to the needs of around six million homes. The PAC also recognised the potential economic benefits, including construction jobs and domestic supply-chain spending, while pressing ministers to ensure promised UK benefits are delivered.
Lessons from previous nuclear projects
The committee highlighted the history of delays and cost increases on comparable reactor projects internationally. The National Audit Office has also warned that no power station of this reactor type has yet been delivered without delays or cost increases, making delivery risk central to the debate over the Sizewell C agreement.
The committee’s conclusions are a parliamentary assessment of financial risk. They do not constitute a finding of wrongdoing by the project’s investors, nor do they mean that the projected upper-cost scenario will necessarily occur.
Sources
House of Commons Public Accounts Committee — Sizewell C report announcement, 28 October 2026