Company Authentication Code is a 6 digit code that can be issued at the time of company is formed. It is work as authorise information equivalent of a company officer's signature.

1. A Complete Guide to Company
Authentication Codes
Company Authentication Code is like a password or a unique identifier. It is issued to all
limited companies in the UK.
After a limited company is formed at Companies House in the UK, Companies House then
issues the newly formed company a Company Authentication Code. Hence, every limited
corporation has got this number, irrespective of whether it is dormant or trading.
A Company Authentication Code usually contains six characters and is alphanumeric.
A Company Authentication Code is mandatory in case of a change of company ownership or
a change of company directors. These changes are usually done by online filing at
Companies House. The Company Authentication Code is used as a replacement for the
physical signature of a director. Therefore, you could say that a Company Authentication
Code is equivalent to a director’s signature. In other words, it is an electronic signature of a
company’s director.
So, it is indeed a pretty important and confidential piece of company data. It is therefore
advised to keep your Company Authentication Code very secure and private. It should only
be accessed by people who are authorized to change your company details.
Why do I need the company authentication code?
You will need your company authentication code every time you attempt online filing via
the Companies House website. For example, you need to provide this code to file your
annual accounts to Companies House or to file your annual returns online. In addition to
that, you will need to use this code to update and/or change any details of your company,
such as your company’s directors, company secretary, or shareholder details.

2. You perform this change using the Companies House online portal or third-party software.
You will be asked to log in to that site using your company authentication code. Only then
will yoube able to make changes. Anyone who has your company authentication code will
be able to change your company’s information.
How to get an authentication code for Companies
House?
To get authentication code for Companies House, register for Companies House
WebFiling.In case, you have registered before then simply log in. Then just click on the link
that says ‘Request an authentication code.’ Enter your company number and choose where
you formed your company.
Then click on continue and finally you get to place your request to get the code.
When you do this, your request is generated to the Companies House. They will send you
the code letter by post at your company’s registered office address.
Where do I find my authentication code for
Companies House?
After you have completed the company formation process at Companies House, you need
to raise a separate request to get the Companies House authentication code. To request
your code, first sign in or register for Companies House WebFiling.
Once you have placed your request, your authentication code can take up to 5 days to arrive
at your registered office address. The steps to be carried out to perform the entire process
of requesting your company authentication code are given below.
1. Go to Companies House Online.
2. Register your email address and password.
3. Select ‘Request an authentication code.’
4. Enter your company registration number.
5. Select ‘Request code.’
You will receive your Companies House Authentication Code Letter at your registered
company address, usually within five business days.

3. How to recover a lost Company Authentication Code?
Companies House authentication code is a very confidential piece of information. Hence, if
you lose it, you cannot retrieve it just through making a phone call. Companies House will
only send this code by post to your business address.
You can go to your online account at Companies House and request a copy of your Company
Authentication Code. For logging in, you will need your company registration number. You
can find your company registration number on the Companies House website as it is publicly
accessible.
On the other hand, if you form your company through a formation agent such as
DataGardener, then it will be very fast and easy to retrieve this code. You can find out your
authentication code just by directly contacting your agent via phone or email. Or you can log
in to your customer profile and fetch your authentication code. It is usually listed there,
along with all other details of your company.
How can I change my company authentication code?
Register to the Companies House WebFiling service. If you have already registered, then just
log in to the WebFiling portal. Choose the country where you registered your company.
Enter your company registration number. Then enter your current company authentication
code. Enter a new authentication code that you prefer. Then click on “Change code” to
confirm the new code. Once you do this, you will get a letter of confirmation from
Companies House at your registered office address.
Conclusion
After you complete the company registration process with Companies House, your company
authentication code is sent to your business address. You can then use these six digital
alphanumeric codes to file documents online and change company details through the
Companies House web portal or third party software. Keep in mind that Companies House
will never contact you to ask for your confidential details about your company such as your
authentication code.
If someone contacts you and claims to be from Companies House and wants to know your
authentication code, you should report it immediately. Also, if you think someone has
gained unauthorized access to your Companies House authentication code, report it to the
fraud team.