When your company is formed, Companies House will send you a letter with your authentication code shortly after. This will be sent to the Registered Office Address. This should be kept safe, and you should record your Companies House authentication code somewhere safe and secure in case you lose your letter. It is required for any changes or filings at Companies House and acts as authorisation for everything. You will need to provide it to your accountant to enable them to file your limited company accounts and confirmation statements.
You can, if you wish, change it to something more memorable. To do this you need to sign in to Companies House WebFiling. Select ‘Company Authentication’ and then change the authentication code there.
If you’ve lost your Companies House authentication code. You can check out our other FAQ on this topic.