More Screenings, But Fewer Interventions: What The UK's Latest NSIA Figures Tell Dealmakers

The UK Cabinet Office has published its fifth Annual Report on the National Security and Investment Act 2021 (NSIA), covering the period from April 2025 to March 2026. The latest figures paint an increasingly striking picture: while the number of transactions reviewed under the regime continues to grow rapidly, the proportion of deals ultimately subject to intervention has fallen to its lowest level since the NSIA entered into force.

This raises an important question for dealmakers: does the Government just happen to be reviewing fewer high-risk transactions, or is the mandatory notification regime capturing an increasing number of deals that pose little or no national security concern? That question is likely to become even more relevant, as the Government's forthcoming reforms to the regime are expected to increase, rather than reduce, notification volumes.

That question aside, the picture is one of a mature and relatively predictable regime, but with some delays being experienced by notifying parties as the screening infrastructure (overseen by the Investment Security Unit (ISU)) struggles to keep up with the increase in notifications. Whilst the Report states that the Government is taking steps to address those delays, transaction parties would be well-advised to factor them into their deal timetables and overall planning.

A rising caseload, but a falling intervention rate

The scale of the increase in notification volumes is striking. The number of notifications reviewed increased 13% year-on-year from 2024/25, and 44% over the two years from 2023/24. 

At the same time, the proportion of cases called in (i.e. subject to a “Phase 2” in-depth review) has remained flat (c.4.5%), so the Government is not being more selective about which cases to subject to a detailed review – even as notification numbers have grown substantially.

On the other hand, 2025/26 saw a low number of transactions subject to intervention. Only nine Final Orders (imposing conditions or blocking/reversing an acquisition) were imposed, and in only four cases did the parties abandon their transaction after call-in. This represents a significant decrease from 2024/25, with the overall intervention rate (taking into account the number of acquisitions abandoned, blocked or subject to conditions, as a proportion of all acquisitions reviewed) halving, and being less than a third of its level in 2022/23 (the first full year of the regime’s operation).

While the low rate of intervention may simply reflect parties' reluctance to pursue high-risk transactions in the current geopolitical climate, it also prompts the question whether the regime is capturing an excessive number of "no-issue" transactions. As we discussed in a recent article, the Government has published proposals to amend the NSIA’s notifiable sectors, but overall these changes are expected to increase, rather than reduce, the number of mandatory notifications. And it is unclear whether plans to exempt internal reorganisations (as part of a separate legislative amendment exercise) will be able to offset this increase.

Timelines remain broadly stable, but with delays creeping in at the front end of the process

Once a notification is accepted, the data suggests that the substantive review process remains reasonably predictable. Every call-in or clearance decision in 2025/26 was made within the statutory 30-working day initial review period, and the average time for a decision has remained unchanged since 2023/24. 

For deals that were called in, the median time from call-in to final notification was 47 calendar working days (i.e. including days where the statutory clock was stopped whilst an information notice remained outstanding) – a little longer than in the preceding year, but broadly in line with 2023/24.

The Report is, however, candid on the fact that there has been an increase in the time taken to accept notifications in the first place, from four working days in 2022/23, to 11 in 2025/26. In relative terms this is significant, but for many transactions the impact may not be material. The delay is put down to the increase in notification volumes, and the Report notes that the Government is taking steps to address it (presumably, by increasing staffing numbers at the ISU, or perhaps making more effective use of technology).

For those cases that proceed all the way to a Final Order, the average time taken remains stable – especially considering the small sample size each year, and the fact that the necessary enquiries are likely to vary significantly on a case-by-case basis.

Prohibitions remain rare

Of the nine Final Orders imposed in 2025/26, eight allowed the relevant acquisition to proceed subject to conditions, and only one required it to be blocked or unwound. This overwhelming preference for conditional clearance has been consistent over the past three years – prohibition remains a genuinely exceptional outcome, even among the small minority of transactions that are called in. Whether this is a reflection of Cabinet Office policy, or higher-risk purchasers having been dissuaded from making investments in sensitive sectors after a significant number of prohibitions in the first year of decisions, is unclear.

Sectors and countries of origin most subject to screening and intervention

Unsurprisingly, Defence has generally been the sector most impacted by the NSIA regime, being relevant to 58% of notifications reviewed in 2025/26 (up from 56% the previous year) and 47% of call-ins. However, whereas it also dominated the Final Orders issued in 2024/25 (9 of 17 Orders), in 2025/26 most Final Orders (5 of 9) related to Advanced Materials, followed by Data Infrastructure and Military and Dual-Use. Therefore, the sectors generating the most notifications and call-ins are not always those in which intervention is ultimately deemed necessary. 

On origin of investment, UK-associated acquirers accounted for the most call-ins (52%, up from 48% in 2024/25) and Final Orders (5 out of 9, compared to 11 out of 17 the previous year) in 2025/26. After the UK, China-associated acquirers featured in 30% of call-ins and a third of Final Orders. This is broadly in line with the preceding year’s outcomes, and is notable given Chinese acquirers accounted for only a tiny proportion of notifications.

Practical implications

Despite the current geopolitical climate and the rising numbers of notifications and call-ins, the outlook for investment screening in the UK remains broadly stable. The overwhelming majority of transactions continue to be cleared without intervention, and the statutory timetable for the initial 30-working-day review period is being met without exception. That said, three practical points are worth factoring into deal-planning.

• It would be prudent to allow for slightly more time at the front end of the review process given the delays in notifications being accepted by the ISU.
• The prominence of certain sectors in last year’s Final Orders – namely Advanced Materials and Data Infrastructure – may warrant a reassessment of the substantive risk in transactions that might not otherwise be seen as involving high-risk activities (i.e. Defence, Military and Dual-Use products).
• For higher-risk transactions, parties should at an early stage consider the sorts of conditions that could be imposed by the Cabinet Office, and whether and how they should be accounted for in deal structuring and documentation. To date, such conditions have generally included a combination of: (i) retaining capabilities and/or assets in the UK; (ii) information-sharing and information security requirements; (iii) corporate governance requirements; and (iv) notification and approval requirements for further transfers, disposals and ownership changes.

Footnote

1. No data was published on calendar working days in the first Annual Report – only statutory working days (which excludes “stop-the-clock” periods). Based on the numbers of statutory working days disclosed in the Annual Reports, these numbers will have been higher than in subsequent years.

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