National Security and Investment notification service: mandatory, voluntary and retrospective forms
These forms contain the questions you'll be asked when letting the government know about an acquisition via the National Security and Investment notification service.
Updates to this page
- From:
- Cabinet Office
- Published:
- 17 December 2021
- Last updated:
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22 August 2026
Show all updates
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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The NSI notification service will be unavailable for much of the day on Sunday 29th June 2025 while essential maintenance takes place. We apologise for any inconvenience caused.
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Updated to remove a message regarding maintenance taking place
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Updated to include a message regarding maintenance taking place
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Removed a message regarding now completed maintenance
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Added a message regarding upcoming maintenance on the system
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Replaced the following documents with their updated version: Mandatory notification form Voluntary notification form Retrospective validation form
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Removed a message regarding now completed maintenance
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Added a message regarding upcoming maintenance on the system
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Replaced the following documents with updated versions: Mandatory notification form Voluntary notification form Retrospective validation form
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Updated the section 'Supply relationships with the UK government' in the document 'Guidance on completing and registering a notification form'
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Removed a message regarding now completed maintenance
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Added a message regarding upcoming maintenance on the system
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Removed a message regarding now completed maintenance on the system.
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Added a message regarding upcoming maintenance on the system
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Removed a message regarding maintenance
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Added a message regarding maintenance
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Removed a note regarding planned maintenance
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Added a note regarding planned maintenance
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Updated with the latest information
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Removed a notice on maintenance work due to its completion.
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Added a notice that the NSI notification service will be unavailable for much of the day on Saturday 17th of February 2024 while essential maintenance takes place.
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Updated contact email address for investment screening
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Replaced the following files with the latest versions: Mandatory notification form Voluntary notification form Retrospective validation form
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Removed notice of maintenance as it has now completed
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Added a notice of upcoming maintenance to the NSI notification service
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Replaced the following documents with updated versions: Mandatory notification form Voluntary notification form Retrospective validation form
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Removed the notice of maintenance as it has now been completed.
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.Updated to provide notice that the NSI notification service will be unavailable for much of the day on Saturday 18th of November 2023 while essential maintenance takes place.
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Removed note regarding maintenance work as it has completed
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Added a message to inform users that the NSI notification service will be unavailable for much of the day on Saturday 28th October 2023 while essential maintenance takes place.
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Replaced the following documents with new versions: Mandatory notification form Voluntary notification form Retrospective validation form
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Updated to reflect the maintenance work was completed and the service is available again.
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Added a note that the NSI notification service will be unavailable for much of the day on Saturday 23rd of September 2023 while essential maintenance takes place. We apologise for any inconvenience.
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Added a note to inform users that the NSI notification service will be unavailable for much of the day on Saturday 8th and Sunday 9th of July 2023 while essential maintenance takes place. We apologise for any inconvenience.
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Updated the document: Guidance on completing and registering a notification form
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The NSI notification service will be unavailable for much of the day on Monday 10 April 2023 while essential maintenance takes place. We apologise for any inconvenience.
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The NSI notification service will be unavailable on Saturday 4 March 2023 while essential maintenance takes place.
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NSI notification service back online.
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The NSI notification service will be unavailable on the weekend of 14-15 January 2023 while essential maintenance takes place. We apologise for any inconvenience.
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Content relating to forms has been moved from the Market Guidance Notes July 2022 and incorporated into this guidance.
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Guidance updated to reflect new time limits for users to access their notifications on the notification portal.
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Guidance updated to reflect new features added to the online service starting on 7 October 2022.
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The NSI notification service will be unavailable from 4:00pm Sunday 20 March to 9:00am Monday 21 March 2022, due to routine maintenance work. If you have any notifications in progress they will not be affected.
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The National Security and Investment (NSI) Act came into force on 4 January 2022. The new rules have now started and the National Security and Investment notification service is open.
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First published.
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Documents
Mandatory notification form (PDF)
PDF, 355 KB, 24 pages
Voluntary notification form (PDF)
PDF, 260 KB, 32 pages
Retrospective validation form (PDF)
PDF, 247 KB, 24 pages
National Security and Investment (NSI) Act declarations A and B
PDF, 172 KB, 2 pages
Details
You may need to tell the government about certain acquisitions before you can go through with them. You do this by completing and submitting a form through the National Security and Investment notification service - see link below.
This page contains:
- guidance on completing and registering a notification form
- copies of the forms which contain the questions you’ll be asked when letting the government know about an acquisition via the notification service
Before you submit your notification please check the guidance on the National Security and Investment Act to see if you need to complete a form.
Once you are ready, Submit a notification through the NSI service.