This guide is maintained as a current resource for July 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Companies House authentication code explained in detail, including its purpose, how it is used, how to obtain or replace it, and its role in UK company filings. A clear guide to secure company administration and online filing requirements in England and Wales.
The Companies House authentication code is a security feature used in the United Kingdom's company filing system. It enables authorised individuals to file information and make changes on behalf of a registered company through the online services provided by Companies House.
Every limited company registered in England and Wales is issued this code when it is incorporated or when online filing access is first set up. It functions as a form of digital password linked to a specific company, ensuring that only authorised users can submit statutory filings.
Understanding how this code works is essential for company directors, company secretaries, accountants, and authorised filing agents.
What Is the Companies House Authentication Code?
The authentication code is a unique six-character alphanumeric code assigned to each company. It is used to verify identity when accessing online filing services.
It is not publicly available and should be treated as confidential. The code is linked directly to the company rather than to an individual user.
Without this code, it is not possible to:
- File annual accounts online
- Submit confirmation statements
- Change company details through online services
- Appoint or remove company officers electronically
- Authorise third-party filing agents
Purpose of the Authentication Code
The main purpose of the authentication code is to secure the integrity of the UK company register and prevent unauthorised filings.
It serves three key functions:
1. Identity verification
It confirms that the person submitting filings has permission from the company to act on its behalf.
2. Access control
It restricts access to sensitive company filing functions, ensuring only authorised users can update official records.
3. Fraud prevention
It reduces the risk of fraudulent changes being made to company details, such as director appointments or registered office addresses.
How the Authentication Code Is Used
The code is used when logging into or authorising actions within Companies House online services.
Typical use cases include:
- Registering for online filing services
- Linking an accountant or formation agent to a company
- Submitting statutory documents
- Updating company information
- Authorising bulk filing software used by professionals
In practice, the code is entered alongside the company registration number when accessing the online system. Once verified, the user can carry out permitted filing activities.
How to Obtain the Authentication Code
The code is issued automatically in several ways:
At company formation
When a new company is incorporated, the code is sent to the registered office address by post.
After registration
If not received or lost, the company can request a replacement through the Companies House service. The replacement is typically sent to the registered office address for security purposes.
Through authorised agents
Accountants or company formation agents may assist in obtaining or resetting the code, but it is always issued to the company itself, not the agent.
Security and Confidentiality
The authentication code must be kept secure. It has the same importance as a password for accessing company records.
Key security considerations include:
- It should only be shared with trusted individuals
- It should not be published or stored in unsecured systems
- It should be updated if there is a risk of compromise
- It should be restricted to authorised company officers or advisers
If the code is disclosed to unauthorised parties, there is a risk of fraudulent filings or unauthorised changes to company records.
What to Do If the Code Is Lost or Compromised
If the authentication code is lost, forgotten, or suspected to be compromised, the company can request a replacement.
Typical steps include:
- Request a new code via the official Companies House process
- Provide company registration details and verification information
- Wait for the new code to be sent to the registered office address
- Replace the old code in all authorised systems and with any agents
Once a new code is issued, the old code is usually invalidated for security reasons.
Common Uses in Company Administration
The authentication code is central to most routine corporate filings. It is commonly used for:
- Filing the confirmation statement (previously annual return)
- Submitting annual accounts
- Updating shareholder information
- Changing registered office address
- Appointing or removing directors and secretaries
- Registering charges and mortgages
Without it, companies must rely on paper filings, which are slower and less commonly used.
Who Needs the Authentication Code?
The code is relevant to anyone responsible for filing company information, including:
- Company directors
- Company secretaries
- Accountants and bookkeepers
- Formation agents
- Legal representatives handling corporate filings
Each company typically has one code, although access may be shared within authorised teams.
Risks of Misuse
Misuse of the authentication code can lead to serious administrative and legal issues.
Potential risks include:
- Unauthorised changes to company records
- Loss of control over company filings
- Delays in correcting incorrect filings
- Possible investigations if fraud is suspected
Companies are encouraged to review access regularly and revoke use by any unauthorised individuals.
Practical Considerations for Businesses
To manage the authentication code effectively, companies should:
- Store it securely in a password manager or secure file system
- Limit access to senior authorised personnel
- Update it if staff or advisers change
- Keep records of who has access to filing systems
- Request a new code if there is any doubt about security
Proper management helps ensure compliance with filing obligations and reduces administrative risk.
Key Takeaways
The Companies House authentication code is a key security feature used to access and manage online company filings in the UK. It verifies authority, protects company data, and enables efficient electronic submissions to Companies House.
It is essential for incorporating companies, filing statutory documents, and maintaining accurate company records. The code must be kept secure, shared only with authorised individuals, and replaced immediately if compromised.
