Companies House Authentication Code Guide: Get, Change & Reset

In the modern landscape of UK business administration, digital efficiency isn't just a luxury—it’s a legal necessity. If you are a director, shareholder, or company secretary of a UK limited company, the Companies House Company Authentication Code is arguably the most important six-digit string of characters you will ever own.

As we move through 2026, Companies House has significantly modernized its systems.With the full implementation of the Economic Crime and Corporate Transparency Act, the way we interact with the UK's registrar has changed. This guide provides an exhaustive deep dive into everything you need to know about the Company Authentication Code, how to manage it, and why it is the "digital key" to your business’s corporate identity.

What is a Company Authentication Code?

The Company Authentication Code is a unique six-digit alphanumeric code issued by Companies House to every limited company and Limited Liability Partnership (LLP) registered in the United Kingdom.

Think of this code as your company’s official digital signature. Just as a handwritten signature authorizes a paper document, this code authorizes digital filings.Without it, you cannot update your company's records online.

Why Does Your Company Need One?

Under current UK law, companies must maintain an accurate public record. The authentication code allows authorized individuals to:

Verify their identity (now a mandatory requirement in 2026).

Submit annual accounts and confirmation statements.

Update director details or change the registered office address.

Ensure the business remains in "Good Standing" with the Registrar.

Where and How is the Code Used?

The code isn't just for the standard Companies House WebFiling portal. In 2026, its utility extends across several critical platforms:

Companies House WebFiling: The primary portal for most small to medium-sized businesses to file documents directly.

Find and Update Company Information (Service): Used for real-time updates and public record management.

Third-Party Software: Many businesses use accounting software (like Xero, FreeAgent, or Sage) to file directly.These platforms require your authentication code to "bridge" the data to Companies House.

Formation Agents: If you used an agent to incorporate, their software uses this code to manage your company’s secretarial duties.

How to Get Your Company Authentication Code

Whether you are a new startup or an established firm that has misplaced its credentials, obtaining a code is a structured process.

1. For Newly Incorporated Companies

If you recently registered your company through Companies House, the code is automatically generated.It is sent via physical post to your registered office address and usually arrives within 5 working days of incorporation.

2. For Companies Formed via Agents

If you used a formation agent, the process is even faster. Most agents provide the code immediately within your online client dashboard. Log in to your agent's portal and look for a section labeled "Company Credentials" or "Auth Code."

3. Requesting a Code via WebFiling

If you don't have your code, follow these steps to have one posted to you:

Step 1: Visit the Companies House WebFiling site.

Step 2: Sign in or create a WebFiling account (this requires an email and password).

Step 3: Click on "File for a company."

Step 4: Enter your 8-digit Company Registration Number (CRN).

Step 5: Select the link "Help with authentication code" and then choose "I do not have an authentication code."

Step 6: Confirm the request. Companies House will post the code to your registered office address.

Security Note: For privacy reasons, Companies House will never give out an authentication code over the phone or via email.It must be sent to the registered office address on record.

Requesting a Code to a Director's Home Address

While the standard procedure is delivery to the registered office, a legacy service from the COVID-19 era remains active for specific circumstances. This allows a director to receive the code at their residential address listed on the register.

Eligibility Criteria

You cannot use the home-delivery service if:

The company has filed any document online in the last 30 days.

The company is based outside the UK.

The company is dissolved or in liquidation.

The entity is not a Limited Company or LLP.

How to Request

Access the "Request an authentication code to a home address" service on GOV.UK.

Sign in with your Companies House account (Note: This is often different from your WebFiling login).

Provide the company number and select the director who should receive the code.

Wait approximately 5–10 working days for postal delivery.

Filing Online: The Benefits of Using Your Code

By 2026, Companies House has moved toward a "digital first" mandate. Using your code to file online is no longer just a convenience; it is the most secure way to operate.

What Can You File?

Confirmation Statements: The annual "snapshot" of your company's data.

Annual Accounts: Including micro-entity and dormant accounts.

Director Changes: Appointing new officers or notifying the registrar of resignations.

Share Allotments: Issuing new shares to investors.

Address Changes: Moving your registered office or SAIL address.

Online vs. Paper Filing

How to Change or Reset Your Code

Is your current code too hard to remember? Or perhaps an employee who knew the code has left the company? You can change your code at any time.

Log In: Access WebFiling with your email and password.

Select Company: Enter your company number and country of registration.

Enter Current Code: You must provide the existing code to authorize a change.

Access Settings: Look for "Company Authentication" on the left-hand menu.

Choose New Code: Enter a new 6-digit alphanumeric code.

Confirm: Once changed, the update is immediate. A confirmation letter will still be sent to the registered office for security audit purposes.

Security Best Practices for Your Company Code

Your authentication code is as sensitive as your bank's PIN.If a fraudster gains access to it, they could potentially "hijack" your company by changing directors or even changing the registered office to redirect mail.

Need-to-Know Basis: Only share the code with your accountant, company secretary, or a trusted formation agent.

Regular Updates: Change the code annually or whenever there is a change in your management structure.

Verify Identity: In 2026, remember that the Company Authentication Code is for the entity, but you also have a Personal Code for your identity. Do not confuse the two.

Avoid Phishing: Companies House will never call you to ask for your code.

If someone asks for it over the phone, hang up.

What to Do if You Lose Your Code

Losing your code is a common issue, but it can be stressful if a filing deadline is approaching.

Check with your Agent: If you used a formation service, they likely have it on file.

Search your Emails: Look for your "Incorporation Documents" or "Welcome Pack" if you are a relatively new business.

Request a Reminder: Use the WebFiling "Help" section. Companies House will usually send a reminder of the existing code rather than generating a new one, unless you specifically request a reset.

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Questions Clients Commonly Ask

1. Does the company authentication code expire?

No, the code remains valid indefinitely unless you manually change it or the company is dissolved.

2. Can I have multiple authentication codes for one company?

No, there is only one active authentication code per company at any given time.

3. Is the authentication code the same as my UTR number?

No. The authentication code is for Companies House (filing), whereas the Unique Taxpayer Reference (UTR) is for HMRC (tax).

4. Can my accountant file for me without the code?

No. Even if an accountant uses their own professional software, they will require your company's authentication code to link the filing to your record.

5. What happens if I enter the wrong code too many times?

For security, Companies House may temporarily "lock" your ability to file online if multiple incorrect attempts are made. You may need to wait or request a new code.

6. Is the code case-sensitive?

Yes, the alphanumeric code is case-sensitive. Always enter it exactly as it appears on your official letter.

7. Can I change my code to something with special characters?

No, it must be a six-digit alphanumeric code (a mix of letters and numbers only).

8. Do I need a new code if I change my company name?

No, the code is linked to your Company Registration Number (CRN), which never changes, even if the name does.

9. Why can't Companies House just email the code?

To prevent digital identity theft and ensure the code reaches a verified physical location associated with the business.

10. How long does the code take to arrive by post?

Typically 5 working days, though it can take up to 10 days during peak periods.

11. Can I use the code for HMRC filings?

While some joint filing services exist, HMRC generally uses its own Government Gateway credentials.

12. What is the PROOF scheme?

The Protected Online Filing (PROOF) scheme is a free service that prevents paper filings from being accepted, ensuring only those with the authentication code can make changes.

13. Do LLPs have authentication codes?

Yes, Limited Liability Partnerships are issued authentication codes just like limited companies.

14. Can I see my code on the public Companies House register?

No. The code is private. Only the company registration number and office address are public.

15. What is the "Personal Code" I keep hearing about in 2026?

The Personal Code is part of the new Identity Verification rules. It identifies you as an individual, whereas the Authentication Code identifies the company.

Disclaimer: The information provided in this article is for general informational and research purposes only. Company details, features, services, and market positions may change over time. Readers are advised to visit official company websites and conduct independent research before making any business decisions or purchasing services.