UK NSI Act — the verified record, live

The National Security and Investment Act 2021 established the UK's standalone investment screening regime, in operation since January 2022. It requires mandatory notification and clearance of acquisitions of control over entities active in seventeen sensitive areas of the economy — including defence, energy, artificial intelligence, quantum technologies, semiconductors and communications — and gives the government a call-in power over a much wider set of transactions, exercisable up to five years after completion where national security risks arise. Completing a notifiable acquisition without approval renders it void. The regime is administered by the Investment Security Unit, which sits in the Cabinet Office, with final decisions taken by the Chancellor of the Duchy of Lancaster. Most notified deals clear quickly, but a steady flow of final orders — conditions, divestments and prohibitions, frequently involving acquirers linked to China — plus consultations on refining the mandatory sectors, keep the regime prominent in UK deal execution and national security policy.

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as of 2026-08-31 · refreshed from scheduled releases

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Frequently asked

Which transactions must be notified under the NSI Act?

Acquisitions of control — generally crossing 25%, 50% or 75% shareholding or voting thresholds, or acquiring blocking rights — over entities carrying on specified activities in the UK within the seventeen mandatory sectors must be notified and cleared before completion. Asset acquisitions and deals outside the mandatory sectors are not notifiable but can be called in, and voluntary notification is available to obtain certainty.

Who decides NSI cases?

The Investment Security Unit in the Cabinet Office administers the regime, screening notifications and supporting assessments, but statutory decisions — clearance, call-in, conditions or prohibition — are taken by the Chancellor of the Duchy of Lancaster as the responsible Secretary of State. Decisions are reviewable by the courts on judicial review principles, with closed material procedures available for sensitive evidence.

What happens if a notifiable acquisition is not notified?

The transaction is legally void, and the acquirer risks civil and criminal sanctions, including fines of up to 5% of worldwide turnover or £10 million, whichever is higher, and potential imprisonment for individuals. The government also retains the power to call in non-notified transactions for up to five years after completion, or six months after it becomes aware of the deal.

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