UK MPs Demand Six-Monthly Sizewell C Cost Reports as Public Bears Nuclear Project Risk

A British parliamentary spending committee is demanding that the government disclose Sizewell C's cost forecasts to the public every six months, rather than the annual updates currently envisaged, after warning that the nuclear project's financing structure leaves households and taxpayers carrying substantial risks.

The House of Commons Public Accounts Committee published its report on 28 October 2026. It examined the construction and financing arrangements for the planned power station in Suffolk, rather than issuing a new planning approval or finding that a cost overrun has already occurred. Its estimated construction-cost range is £40.5 billion to £47.7 billion, with construction expected to finish between 2039 and 2043. These are forecasts, not final bills.

The accountability gap is concrete. Shareholders are expected to receive six-monthly project updates verified by an independent technical adviser. The Department for Energy Security and Net Zero and Sizewell C Ltd, however, currently plan to provide Parliament with only an annual report. The committee wants both bodies to report twice a year on actual and forecast costs, schedule changes, milestones, public-sector exposure, consumer-bill impacts and expected investor returns. It also recommends releasing the underlying figures in machine-readable form, with explanations for any data withheld for commercial or security reasons.

The committee illustrated the stakes with a higher-cost scenario. If construction reaches £47.7 billion, it estimates that consumers could pay an additional £9.8 billion during construction and another £12 billion over the station's operating life, while private investors would have to provide only £30 million in additional capital. Those amounts describe possible effects under the committee's scenario; they are not charges already levied, established losses or a prediction that the upper cost threshold will necessarily be reached.

The UK government holds 44.9% of the project company's equity, but public financing and guarantees expose the state to substantial risks. The committee questions whether a minority ownership stake and board influence will always allow ministers to protect consumers if investor and public interests diverge. It has asked the company to provide, within three months, the scenario analysis underpinning its cost and schedule thresholds, including assessments of the likelihood of different outcomes.

The department and developer argue that reusing the Hinkley Point C reactor design and applying construction lessons should reduce delivery risk. Ministers also point to the potential for low-carbon electricity generation and future system savings. Those prospective benefits deserve scrutiny alongside financing costs; the parliamentary report does not establish that the plant will fail, nor does it invalidate existing approvals.

For electricity customers, the next measurable test is whether the government accepts the committee's proposed reporting timetable and releases comparable cost and risk data. This report draws on the public parliamentary document, independently corroborated by specialist and national reporting; TFNOS has not independently audited the project accounts.