Lost your Companies House authentication code? Here's how to get it back.

What the code is

The authentication code is a 6-character code of letters and numbers that Companies House issue to each company. It authorises what is filed online, as an officer's signature would.^{(source 1)} You need it to file online, whether through Companies House's own service or through software.^{(source 2)} It isn't the same as the personal code a person gets when they verify their identity.^{(source 3)}

How to get it again

1. 1

   Step 1: Sign in to Companies House WebFiling

   To ask for it, create an account or sign in to Companies House WebFiling and follow the steps.^{(source 4)}

2. 2

   Step 2: Wait for the post

   It comes by post to the registered office and can take up to 10 working days. If the company already has a code, they send a reminder of it.^{(source 5)} If you can't get to the registered office address, they can send it to your home address instead.^{(source 6)} They can't email it or read it out over the phone.^{(source 7)}

3. 3

   Step 3: Keep it somewhere safe

   Treat it like a bank card PIN: anyone who knows it can change the company's details online.^{(source 8)}

Why not to leave it

Companies House ask you not to wait until the accounts are due to request it, because delivery can take longer in busy periods.^{(source 9)}

If your accounts are already late, allow for the time the letter takes to arrive. Our guide to a missed Companies House deadline covers the rest.

Changing the code

You can change or cancel the code by signing in to WebFiling.^{(source 10)} If you change it, tell anyone else who files for the company: the old code stops working.^{(source 11)}

If someone asks you for it

If someone claiming to be from Companies House asks for the code, report it to Companies House as fraud straight away.^{(source 12)}

How standing.tax looks after it

• You give your company's authentication code once. It's kept encrypted, never shown again, and put only on the filings you approve.
• The most sensitive details, such as National Insurance numbers, your authentication code and your connection to HMRC, are encrypted before they're stored, and never written to our logs.