Lost Your Companies House Authentication Code? Here’s What to Do
Losing your Companies House authentication code is more common than you’d think — and without it, you can’t file a Confirmation Statement, submit accounts, or update your company’s details online. This guide from Filing Accounts UK explains exactly what the authentication code is, how to request a replacement, and how long it takes, using only verified facts from official Companies House guidance.
At Filing Accounts, we help UK limited company directors stay compliant with Companies House filing requirements. You can check your company’s current filing status on the Companies House public register at any time.
What Is a Companies House Authentication Code?
The company authentication code is a 6-character alphanumeric code issued by Companies House to every company when it’s incorporated. According to official Companies House authentication code guidance, it acts as the equivalent of a company officer’s signature, authorising any information filed online on the company’s behalf. You need it to file through Companies House WebFiling or through commercial/third-party filing software, including for:
- Filing your Confirmation Statement (CS01)
- Filing your Annual Accounts
- Appointing or removing a director (AP01 / TM01)
- Updating your registered office address or other company details
Without it, none of these can be filed online. Note that the authentication code is not the same as the Companies House “personal code,” which is a separate code issued to individual directors and PSCs once they complete identity verification.
How to Request a Replacement Authentication Code
Step 1: Sign In to (or Register for) Companies House WebFiling
Go to the Companies House WebFiling service and sign in with your existing account, or register for a free account if you don’t already have one.
Step 2: Select “Request an Authentication Code”
From your WebFiling account, choose the option to request an authentication code. You’ll be asked to confirm your company number and details.
Step 3: Confirm Your Registered Office Address
Companies House will show your company name, number, and registered office address. Check this carefully — your new code will be posted to this address, so it must be correct and able to receive mail. If you have moved and no longer have access to your old code, you may need to contact Companies House directly to update your address before a new code can be issued.
Step 4: Wait for Your Code to Arrive by Post
Companies House will only ever send your authentication code by post — for security reasons, it is never issued by email or over the phone. According to official guidance, delivery can take up to 10 working days, particularly during busy filing periods, so don’t wait until your deadline is close to request a replacement.
Step 5: Activate and Store Your New Code Securely
Once your new code arrives, you can use it to file online immediately. Store it securely — ideally in a password manager rather than a shared document or email — and update anyone who files on your behalf, such as your accountant, since the old code will no longer work once a new one is issued.
Can You Change Your Authentication Code to Something Memorable?
Yes. If you still have access to your current code, you can sign in to WebFiling and change it to something easier to remember, provided it isn’t easy to guess. If you change your code, you must tell anyone else who files online on your company’s behalf, such as your accountant, as they will not be able to use the old code once it has been changed.
Can the Code Be Sent to a Home Address Instead?
In certain circumstances, Companies House allows you to request an authentication code be sent to a home address instead of the registered office. This is a useful option if you no longer have reliable access to your registered office address.
Authentication Code Security: What to Know
Companies House advises treating your authentication code with the same care as a bank card PIN. Anyone who has your code can make changes to your company’s details online, so it’s worth keeping the following in mind:
- Companies House will never ask for your code over the phone. If someone contacts you claiming to be from Companies House and asks for your authentication code, report it as fraud immediately.
- Change your code if it’s known by someone no longer authorised to file for your company — for example, a former employee or a previous accountant.
- Monitor your company’s public record periodically for any changes you don’t recognise, particularly if you suspect your code may have been compromised.
Why You Shouldn’t Wait to Request a Replacement
If you can’t file because you’ve lost your authentication code, your Companies House deadlines don’t move to accommodate you. A late Confirmation Statement is a criminal offence and can ultimately lead to your company being struck off the register, while late Annual Accounts carry automatic financial penalties starting at £150. Given that a replacement code can take up to 10 working days to arrive by post, requesting it as soon as you realise it’s lost — rather than waiting until closer to a filing deadline — is the best way to avoid missing a deadline altogether.
For more on what’s at stake, see our guide on Confirmation Statement vs Annual Accounts.
Common Mistakes to Avoid
Waiting Until the Deadline Is Close
Since a replacement code can take up to 10 working days by post, requesting one at the last minute risks missing your filing deadline entirely.
Expecting the Code by Email
Companies House will never email or read out your authentication code over the phone. It is only ever sent by post.
Not Updating an Outdated Registered Office Address
If your registered office address is out of date, your new code could be posted somewhere you can no longer access it, causing further delay.
Confusing the Authentication Code With the Personal Code
The authentication code belongs to the company; the personal code belongs to an individual director or PSC as part of identity verification. They are not interchangeable.
Sharing the Code Insecurely
Emailing or messaging your authentication code without care creates unnecessary risk. Treat it with the same security as a password.
Frequently Asked Questions
How do I get a new Companies House authentication code?
Sign in to Companies House WebFiling, select “request an authentication code,” confirm your company details, and a new code will be posted to your registered office address.
How long does a replacement authentication code take to arrive?
Official Companies House guidance states it can take up to 10 working days, especially during busy periods, so request it as early as possible.
Is there a fee to request a replacement authentication code?
No. Requesting a replacement authentication code through Companies House WebFiling is free.
Can Companies House email or read me my authentication code?
No. For security reasons, it is only ever sent by post. Companies House will never ask for it over the phone.
Can I change my authentication code to something easier to remember?
Yes, if you still have your current code, you can change it via WebFiling, as long as the new code isn’t easy to guess.
What’s the difference between the authentication code and the personal code?
The authentication code authorises filings for the company as a whole. The personal code is issued to an individual director or PSC once they complete identity verification, and is separate from the company’s authentication code.
Can my accountant use my authentication code?
Yes, but if you change your code you must tell them, as the old code will stop working immediately.
Need Help Filing With Companies House? Talk to Filing Accounts UK
Losing your authentication code at the wrong moment can put a filing deadline at risk. At Filing Accounts, we handle Confirmation Statements, Annual Accounts, and other Companies House filings for UK small businesses, so a lost code doesn’t turn into a missed deadline.
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