Companies House Authentication Code: How to Find, Request and Change It

Last updated: August 10, 2026 4 min read

A Companies House authentication code is the company-specific credential used to authorise online filings. It acts as the electronic equivalent of a company officer’s signature and can be located, requested or changed through Companies House services.

Person typing on a keyboard at night with a digital padlock and password overlay representing a Companies House authentication code

Written by: Himani MH

Business Compliance Research and Content Associate

Expert Review by: Robert Carter

UK Company Formation and Compliance Adviser

Key Highlights

A company authentication code contains six alphanumeric characters and belongs to a specific company.
Companies House sends the original code or a requested reminder by post to the company’s registered office.
Allow up to 10 working days for delivery. Companies House replaced its previous five-day guidance with this timeframe on 26 August 2025.
You need the code to file a confirmation statement online, but you can file a paper form CS01 without it.

What is a Company Authentication Code?

Your company authentication code is a six-character alphanumeric code issued by Companies House to each company. It authorises information filed online and acts as the electronic equivalent of a company officer’s signature.

The code belongs to the company. It is separate from a Companies House personal code, which belongs to an individual who has verified their identity. Companies House requires the personal code when identity verification details must be supplied, including for director appointments and confirmation statements.

Treat this code like your bank PIN. Keep it secure. You’ll need it whenever you file statutory documents or make changes to your company details, including when you:

Submit your confirmation statement
File annual accounts or dormant accounts
Appoint or remove directors and secretaries
Change your registered office address
Update Persons with Significant Control (PSC)
Change your company name

You’ll use the code through Companies House WebFiling, the Find and update company information service, or approved company formation software.

How To Locate Your Companies House Authentication Code?

Use these steps to locate an existing code before requesting a reminder:

Check the post received at the registered office: Companies House automatically posts the original authentication code to the company’s registered office after incorporation. Allow up to 10 working days for delivery.
Check your formation agent’s customer account: If an agent formed the company and the code has not since been changed, the code may be available in the company details held in your online account.
Ask an authorised filer: If you previously shared the code with a trusted accountant, company secretary or formation agent, check whether they hold the current version.

Treat the code with the same care as a bank card PIN and share it only with people authorised to file for the company.

How To Request a Lost Companies House Authentication Code?

If you cannot locate the code, request a reminder through Companies House WebFiling:

Sign in to Companies House WebFiling using GOV.UK One Login, or create sign-in details.
Select ‘Your companies’ or ‘File for a company’.
Enter the company details.
Select ‘Help with authentication code’.
Select ‘I do not have an authentication code’ and submit the request.

If the company already has a code, Companies House will post a reminder of that code to its registered office. It can take up to 10 working days to arrive, and Companies House will not send it by email or provide it over the phone.

If you cannot access the registered office and meet the service conditions, you can request delivery to an active officer’s home address. The officer’s home address held by Companies House must be current.

Insight When Can the Code Be Sent to a Home Address?

The home-address delivery service is only available for eligible UK limited companies and LLPs. It cannot be used if the company has filed online within the last 30 days, is dissolved, or is based outside the UK. The code is sent to an active officer’s home address.

How To Change Your Companies House Authentication Code?

Follow these steps to change the code:

Sign in to Companies House WebFiling using GOV.UK One Login.
Select ‘Company authentication’.
Enter a new six-character alphanumeric code that is difficult to guess.
Re-enter the code to confirm it.
Select ‘Change code’.

Once the change takes effect, the previous code will no longer work. Tell your accountant, company secretary, formation agent or anyone else authorised to file for the company.

Insight Keeping Your Authentication Code Secure

Change the code if it is known by someone you no longer trust or who no longer files for the company, such as a former employee or accountant. Companies House will never ask you to disclose the code over the phone.

Companies still receive and use authentication codes after WebFiling’s move to GOV.UK One Login. GOV.UK One Login provides access to WebFiling, while the authentication code authorises online filings for a specific company. You may need to enter each company’s authentication code when connecting your WebFiling account.

Identity verification is a separate process. A Companies House personal code links a verified individual to director or PSC roles and is required for specified submissions, including director appointments and confirmation statements.

Other Identifiers You May Encounter When Running a Company

These identifiers serve different purposes and should not be confused with a Companies House authentication code:

VAT registration number: A nine-digit number issued by HMRC when a business registers for VAT. It identifies the business for VAT returns, invoices and payments.
Company Unique Taxpayer Reference (UTR): A 10-digit reference issued by HMRC to identify a company for Corporation Tax.
EORI number: An Economic Operators Registration and Identification number that a business may need when moving goods across certain UK and international borders.
D-U-N-S Number: A nine-digit business identifier issued by Dun & Bradstreet. It is not a government identifier and is not required for every UK company.
Employer PAYE reference: A reference issued by HMRC when a business registers as an employer. It identifies the employer’s PAYE scheme.
Company registration number (CRN): A unique identifier issued by Companies House when a company is incorporated. It identifies the company on the public register and official filings.
Accounts Office reference: A 13-character HMRC reference used as the payment reference when paying an employer’s PAYE bill.
Tax Identification Number (TIN): A general international term for an identifier used for tax purposes. The UK uses existing identifiers, such as a UTR or National Insurance number, depending on the person, entity and reporting context.
Right to work share code: A code generated by an eligible individual that allows an employer to check the types of work they can perform and how long they can work in the UK.

FAQs Companies House Authentication Code

Can I File a Confirmation Statement Without an Authentication Code?

Yes. You need an authentication code to file online, but you can submit paper form CS01 without one. Paper filing costs £110, compared with £50 online, and takes longer. You must still provide the required identity verification details for current directors.

What Is the Difference Between an Authentication Code and a Personal Code?

An authentication code has six characters, belongs to a company and authorises online filings. A personal code has 11 characters, belongs to a verified individual and is used for identity verification requirements, including director appointments and confirmation statements.

Can an Accountant or Company Secretary Use a Company Authentication Code?

Yes. A company can share its authentication code with a trusted accountant, company secretary, formation agent or other authorised filer. Commercial filing software users also need a presenter ID and presenter authentication code. If they do not have the company code, a reminder can be requested through WebFiling.

What Should I Do If the Authentication Code Does Not Arrive?

Check the registered office address on the Companies House register. If it is wrong, update it before requesting again. Companies in the PROOF scheme should contact Companies House because protected details cannot be changed on paper. If 10 working days have passed, contact Companies House.

Article byHimani MH

Himani MH is a content and research associate at Your Company Formations with five years of experience producing guidance on UK business compliance, HMRC processes, identity verification, and business banking. She focuses on making regulatory and process-driven content clear and accessible for entrepreneurs and new business owners.