How to request your Companies House authentication code and Corporation Tax UTR
Two different company credentials, two official request routes. Here’s where to request replacements, where the letters go and why you should allow time before you need to file.
By In Front Accounting · Published 22 October 2026
The short answer
- A company authentication code authorises online filings at Companies House. Your company’s Corporation Tax UTR identifies the company for HMRC tax work; it is not needed for a Companies House confirmation statement.
- Request a Companies House code through WebFiling. It is posted to the registered office, not emailed or given by phone. Official guidance says up to 10 working days, potentially longer during busy periods.
- For a limited company’s lost Corporation Tax UTR, use HMRC’s online request route. HMRC posts it to the business address registered with Companies House.
1. Request the company authentication code through WebFiling
Follow Companies House’s official authentication-code guidance to its WebFiling service. Sign in or register, select the request for an authentication code, and provide the company number and the details requested by the official service. The code is a six-character alphanumeric company code used to authorise online filings.
The standard letter goes to the company’s registered office. Check that you can receive post there and arrange safe forwarding if you use an address provider. The guidance, last updated 25 September 2026, says delivery can take up to 10 working days and longer when busy. This is an estimate, not a guarantee or an extension to your filing deadline.
Companies House does not send the code by email or provide it by phone. Do not put the code in an email, public form or ordinary chat.
2. If you cannot receive the registered-office letter
The official alternative request service can send a code to an active company officer’s home address where eligible. Use the official eligibility checks rather than assuming any director or anyone monitoring a company can use this route.
The service lists restrictions, including companies that filed online in the last 30 days, companies outside the UK, entities other than limited companies or LLPs, and dissolved companies. Check the current service conditions before applying. Postal delivery still takes time and is not guaranteed by a particular date.
3. Request a lost Corporation Tax UTR from HMRC
First check previous HMRC company tax letters or returns. If you still cannot find the company’s UTR, open GOV.UK: find your UTR number and follow the section for a limited company’s Corporation Tax UTR to request it online. Enter the company details requested by HMRC’s service, not your personal tax reference.
HMRC says it will post the Corporation Tax UTR to the business address registered with Companies House. Confirm you can receive that letter; do not assume it will arrive at your home or your accountant’s address. We do not promise an HMRC delivery date.
4. Keep company and personal credentials separate
- Company authentication code: authorises company filings at Companies House.
- Companies House personal code: belongs to an individual after identity verification. It is not the company authentication code. See our personal code guide.
- Company Corporation Tax UTR: the company’s HMRC tax reference.
- Personal UTR: an individual’s Self Assessment reference, separate from the company’s UTR. See how to find your UTR.
5. Request early and share only through an authorised secure process
If an online Companies House filing is approaching and the company authentication code is missing, request it early. The Corporation Tax UTR is relevant to company tax work, not the confirmation statement. Neither requesting a replacement nor marking a portal reminder handled means a filing has been submitted.
Only authorised people should access or share company filing credentials. Free monitoring of a public Companies House record does not prove ownership, directorship or filing authority and does not make In Front Accounting the company’s accountant. Never share a code in a public link, email reply or analytics form.
Need help with your limited company’s accounts and tax?
Explore our limited-company accounting service or contact In Front Accounting to discuss the services you need. An engagement and agreed scope are separate from monitoring.
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Common Questions
Can Companies House email my authentication code?
No. Companies House says the code is sent by post and is not supplied by email or phone.
Is a Corporation Tax UTR needed for a confirmation statement?
No. These are different credentials. A company authentication code is used for online Companies House filing; the company Corporation Tax UTR is for HMRC tax work.
Is my personal UTR the company’s Corporation Tax UTR?
No. A company’s tax reference is separate from an individual’s Self Assessment UTR.
Will requesting a replacement extend a filing deadline?
Do not assume a replacement request extends any deadline. Allow time for post and check the official filing requirements.
Last reviewed 22 October 2026. General UK guidance, not advice for your circumstances. Sources: Companies House authentication codes (updated 25 September 2026); officer home-address request eligibility; HMRC find your UTR guidance. Check official guidance for changes.