Company authentication code: what it is and how to get a new one

A company authentication code is a 6-character code of letters and numbers that Companies House gives each company so it can file online. It works like a director’s signature on a paper form. If you have lost it, sign in to WebFiling and request a new one; it is posted to the registered office and can take up to 10 working days.

What is a company authentication code?

The company authentication code is the company’s online signature at Companies House. You need it to file accounts, a confirmation statement or changes to officers and addresses online.

Companies House’s guidance on authentication codes, last updated on 25 September 2026, says the code is 6 digits long and alphanumeric. Each company has one code, whoever files for it.

Where can you use it?

You can use the code in three places:

• Companies House WebFiling, the free online filing service
• Find and update company information, the newer Companies House service
• Commercial filing software, such as accounts production or company secretarial software

Software filing also needs a presenter ID and presenter authentication code from an online filing account. You cannot file with Companies House through a Government Gateway account.

Authentication code vs personal code

The two codes do different jobs, and people often mix them up.

The personal code is 11 characters long and comes from identity verification. Our guide to the Companies House personal code explains how to find it, and how to verify your identity covers the process.

How to get a new authentication code

You request a code online, and Companies House posts it to the company. Follow these steps.

1. Go to Companies House WebFiling and sign in with GOV.UK One Login. WebFiling has required One Login since 13 October 2025.
2. Add the company by entering its company number.
3. Choose the option to request an authentication code.
4. If the company already has a code, Companies House posts a reminder of the existing code.
5. Wait for the letter at the registered office address. Allow up to 10 working days, and longer in busy periods.

If you cannot get post at the registered office, you can ask for the code to go to a home address instead. Companies House says it cannot send the code by email or tell you it over the phone.

Do not wait until your accounts are due. A code that arrives after the deadline still leaves you with a late filing penalty. Use our filing deadline calculator to check your dates, and see Companies House late filing penalties for the amounts.

Which applies to you?

• If you have the letter but lost the code: sign in to WebFiling and request a reminder.
• If you know the code but someone untrusted also knows it: change it in WebFiling straight away.
• If you are an overseas company: request the code through Find and update company information. Since 25 September 2026 this is the only route, the code goes to the UK establishment address, and it can only be used to file package accounts.
• If your accountant files for you: they may already hold the code. Ask them before requesting a new one.

How to change your authentication code

You change the code by signing in to WebFiling and choosing a new one. You can pick something more memorable, but it should not be easy to guess.

The old code stops working as soon as you change it. Tell anyone else who files for the company, such as your accountant or company secretary, or their next filing will be rejected.

When you connect a WebFiling account to One Login, you may be asked to enter each company’s code to confirm you are still authorised to file for it. Only one person can connect each WebFiling account, according to the Companies House filing guidance.

How to keep the code safe

Treat the code like a bank card PIN, because anyone who knows it can change the company’s details online. Companies House’s fraud guidance recommends that you:

• use a mix of letters and numbers
• share it only with people you trust to file for the company
• change it when a former employee or previous accountant knew it
• sign up to the free Follow service, which emails you when a filing is accepted
• consider the free PROOF scheme, which blocks some paper forms such as registered office and officer changes

Companies House says it will never ask for your code by phone or email. Call 0303 1234 500 (Monday to Friday, 8:30am to 6pm) about a suspicious call or letter, and forward suspicious emails to phishing@companieshouse.gov.uk. Report fraud to Report Fraud on 0300 123 2040.

What to do now

1. Check who in your business, or at your accountant, holds the code.
2. Change it if anyone who has left still knows it.
3. Request a reminder now if no one can find it, well before your next confirmation statement or accounts deadline.

Frequently asked questions

How long does it take to get a Companies House authentication code?

Companies House says it can take up to 10 working days for the code to arrive by post. It can take longer during busy periods.

Can Companies House give me my authentication code over the phone?

No. Companies House cannot send the code by email or tell you it over the phone. It only posts it to the registered office or, if you ask, a home address.

Is the authentication code the same as the personal code?

No. The authentication code belongs to the company and authorises filings. The 11-character personal code belongs to a director or PSC who has verified their identity.

What happens to the old code when I change it?

It stops working immediately. Anyone who files for the company, such as your accountant, needs the new code.

Does my accountant need my authentication code?

Usually, yes, if they file accounts or a confirmation statement for you through software or WebFiling. Share it only with people you trust, and change it if you change accountant.