What the authentication code is
It is a 6-character code made up of letters and numbers, issued by Companies House to your company. Anyone filing online for the company — you, your accountant, or an agent such as us — has to give this code, which is how Companies House knows the filing is authorised. There is one code per company, shared by everyone who files for it, no matter how many directors the company has.
What it is not
- Not your personal code. That is 11 characters (like ABC-1234-5678), belongs to you rather than the company, and comes from identity verification. Most confirmation statement filings need both codes.
- Not your company number. That is the 8-digit number on the public register (e.g. 12345678) and is not secret.
- Not a WebFiling password. Sign-in details get you into an account; the authentication code authorises the filing itself.
Where to look for it
- The letter from Companies House. The code was posted to the registered office shortly after the company was set up, on a letter headed with the company name and number.
- Whoever formed the company. If a formation agent or accountant incorporated it for you, the code was very often sent to them — and they usually still have it on file. This is the quickest place to ask.
- Anyone who has filed before. A co-director, company secretary or bookkeeper who has filed a confirmation statement or a change of address has used the code and may have it saved.
- Your own records. Search your email for the company name alongside "authentication code", and check where the company's statutory papers are kept — the code is often filed with the incorporation certificate.
- The registered office. If that address is an accountant or a service provider, ask them to check the post they received when the company was created.
If a code keeps being refused, check the look-alike characters
Most refused codes are a reading error rather than a wrong code — a character misread from a letter, a photo, or a phone call. Before requesting a replacement, check these:
| Easily confused | What to check |
|---|---|
| 0 and O | Zero is usually narrower than a capital O — count the characters either side if you are unsure. |
| 1, I and l | One, capital i and lower-case L all print similarly on a Companies House letter. |
| 5 and S | A hurried photocopy or a scan of the original letter blurs these two. |
| 8 and B | Common when the code has been written out by hand or read over the phone. |
| 2 and Z | Worth double-checking if the code was forwarded as a photo of the letter. |
Also check you are not using the code for a different company you are involved with, and that the code has not been replaced since you last filed — a newer code cancels the old one.
Guessing doesn't help
Companies House shows how many attempts are left in the session. Those attempts do reset — a later sign-in normally starts a fresh batch — so a refused code isn't something to panic about. What it does cost you is time: nothing is filed until the correct code turns up, and with a deadline approaching that matters more than the attempt counter. So when a code is refused, check it against the original letter rather than trying variations of it, and request a replacement if you can't find the letter — that is the step with the 5-working-day wait in it.
How to get a replacement
Companies House will issue a new code for the company on request. It is posted to the registered office on the public register — it is never emailed or read out over the phone — and takes around 5 working days to arrive at a UK address. Once the new code is issued, the old one stops working, so anyone who files for the company needs the new one.
If nobody can collect post at the registered office, sort that out before requesting the code — otherwise the letter goes somewhere you can't reach. Companies House can talk you through the options, and if you are filing with us we can help you work out the quickest route.
Keeping it safe
The code authorises filings against your company, so treat it like a banking credential: share it only with the people who file for you, and let your accountant or agent know if it is ever replaced. If you have asked us to file, we hold your code against your order for that filing and never publish it.
Filing your confirmation statement with us?
Send us the code through the secure link in our email, or call us on 0161 317 8556 and we'll take it over the phone. If the code you gave us was refused by Companies House, we'll tell you which code we tried, so you can check it against your paperwork — we don't guess at variations. See also how to file a confirmation statement and confirmation statement deadlines.