The company authentication code is a 6 character code that Companies House issues to each company and treats as the equivalent of an officer’s signature for online filing. It belongs to the company, so the directors should control it and share it only with people they trust to file, such as their accountant. Identity verification adds a separate personal code for individuals, and Companies House is moving towards a system where filers must be verified or registered as authorised agents.

What is the company authentication code?

Companies House describes it as a 6 digit alphanumeric code issued to each company, used to authorise information filed online and equivalent to a company officer’s signature. The same code is used for:

  • Companies House WebFiling;
  • the Find and update company information service;
  • commercial filing software.

To file through software, the filer also needs its own online filing account with a presenter ID and presenter authentication code. A Government Gateway account cannot be used to send information to Companies House.

Anyone who knows the code can file most documents for the company online, including changes to its registered office, officers and other details. That is why Companies House tells companies to treat it with the same care as a bank card PIN.

How is the code obtained, and how long does it take?

A code is requested by creating an account, or signing in, on WebFiling. Companies House posts it to the company’s registered office, and its guidance says it can take up to 10 working days to arrive. If the company already has a code, Companies House sends a reminder of it instead. Where the registered office cannot be accessed, the code can be sent to a home address.

Companies House will not send the code by email or give it over the phone. Its advice is not to wait until accounts are due before requesting one, because delivery can take longer at busy times. A code that has to be requested in the last week before a deadline is a common cause of late filing; see why Companies House rejects filings.

Since 25 September 2026, overseas companies can request a code through Find and update company information. It is posted to the UK establishment address and can be used only to file package accounts.

Who should hold the code?

The code belongs to the company, not to its accountant, formation agent or company secretary. In practice the directors should know where it is, and should decide who else may use it. Companies House says to share it only with someone you trust to file for the company.

A sound arrangement for an accountancy practice is:

  • the engagement letter records that the practice is authorised to file named documents for the client using the code; see engagement letters for accountants;
  • the code is held in the practice’s secure systems with restricted access, not in emails or spreadsheets;
  • the practice files only documents the client has approved, since the code acts as the officer’s signature;
  • the client is told that it can change the code at any time.

Directors remain responsible for what is filed and for filing on time, even where an accountant does the work. Companies House’s appeals guidance says relying on an accountant is not likely to be accepted as a reason for late filing.

When should the code be changed?

A code can be changed or cancelled by signing in to WebFiling. Companies House says to change it if it becomes known to someone you do not trust, or to someone no longer authorised to file for the company, such as former staff or a previous accountant. Once it is changed the old code stops working, so anyone else who files for the company must be told the new one.

A change of accountant is the obvious moment. The outgoing practice should not keep using the code once its engagement ends, and the incoming practice should ask the client to change it as part of taking on the work; see professional clearance when changing accountant.

Illustration only

A director falls out with a former business partner who used to handle the company’s filings. The director should change the code at once, check the company’s filing history, and consider joining the free PROOF scheme. Under PROOF, covered forms such as registered office and officer changes can only be filed online, and Companies House rejects paper versions. Companies House’s free Follow service can also send email alerts whenever something is filed.

How is the authentication code different from the personal code?

Companies House stresses that the company authentication code is different from the Companies House personal code, which individuals receive after verifying their identity.

Company authentication code Companies House personal code
Belongs to The company The individual
Format 6 characters 11 characters
Purpose Authorises online filings for the company Confirms the person’s identity has been verified
How issued Posted to the registered office Issued after verification through GOV.UK One Login or an authorised agent

A director uses one personal code for all their appointments. Since 18 November 2025, existing directors provide it in the company’s next confirmation statement, and new directors provide it on appointment or incorporation. The personal code can be shared with someone who files on the person’s behalf, such as an accountant. For the wider rules see Companies House identity verification.

How is the code changing with GOV.UK One Login and identity verification?

From 13 October 2025, WebFiling users have had to sign in through GOV.UK One Login. When an account is connected, Companies House may ask for each company’s authentication code to confirm the user is still authorised to file for it. Only one person can connect each WebFiling account to their One Login, so staff who shared a single login need their own.

The bigger change is who may file. Section 1067A of the Companies Act 2006, inserted by the Economic Crime and Corporate Transparency Act 2023, will require anyone delivering documents to Companies House to be identity verified, or to be an authorised corporate service provider (ACSP) or an officer or employee of one. Legislation.gov.uk shows this section as not yet in force except for regulation making powers. Companies House says identity verification for people who file will be introduced at a later date, and that in the future you may need your personal code to file for a company. You will not need to provide it if you verified through GOV.UK One Login, saved your code to your Companies House account, or are registered as or added to an ACSP account.

What does this mean for accountancy practices?

Companies House says that in the future all agents that file on behalf of clients will need to register as authorised agents, and that registered agents will be able to file for clients from no earlier than November 2026. To register, an agent must be supervised by a UK anti money laundering supervisory body, and the person applying must verify their identity. A limited company or LLP applying also gives its own company number and authentication code. See AML supervision for accountants.

Users added to an authorised agent account do not need to verify their own identity and can file for clients and verify identities. The account owner must tell Companies House about changes, including the agent ceasing to be supervised, within 14 days.

What mistakes should you avoid?

  • Leaving the code with a former accountant or employee.
  • Sending the code by email to people who do not need it.
  • Requesting a code days before a filing deadline.
  • Confusing the company code with a director’s personal code, or with the presenter code used by software.
  • Responding to calls or emails asking for the code. Companies House says it will never ask for it by phone or email.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.