Companies House WebFiling – Security Issue 13.03.2026

Companies House offers a WebFiling service, allowing online submissions of documentation (as opposed to traditional paper submissions).

WebFiling typically requires (1) that you have a profile with and have logged into the service, (2) the registered number of the entity you are filing for, and (3) the authentication code for the entity you are filing for.

This service was temporarily closed between Friday 13 March and Monday 16 March due to Companies House becoming aware of a security issue which could allowed a logged-in user to (after carrying out a specific sequence of actions):

• view certain data belonging to other companies they would not typically be able to access (dates of birth, residential addresses and company registered email addresses); and
• make unauthorised filings (such as regarding accounts or changes of director) for other companies.

This could have occurred between 11 October 2025 (following an update which introduced the security issue) and 13 March 2026.

Next Steps:

Companies House has asked that companies check their details and filing history to ensure that everything appears correct.

If you have any concerns, Companies House has advised:

• that you email enquiries@companieshouse.gov.uk;
• include “WebFiling Issue” in the subject heading; and
• provide evidence of the issues.

Companies should have received an email to their registered email address from Companies House between Tuesday 17 March and Thursday 19 March 2026, which confirmed that:

• this was not a cyber-attack;
• there is no need to reset WebFiling passwords;
• no identity verification data (e.g. passport information or personal codes) was accessed;
• no existing filed documents could have been altered;
• anyone who had applied to protect their personal details under the Companies Act 2006 will not have had their information affected; and
• it was believed that data could not have been extracted in large volumes (a later update on 20 March 2026 has confirmed there was no risk of bulk data transfer).

Updates:

Companies House have confirmed they are actively investigating the security issue, including analysing their own data to identify anomalies.

Updates will be published here: WebFiling issue: information and updates – GOV.UK as the investigation continues.