What is a company registration number (CRN)?

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A CRN (company registration number) is a unique code that Companies House uses to help it quickly and correctly identify a company. A CRN is assigned upon incorporation, which means that limited companies and LLPs (limited liability partnerships) must have one.

Some other types of business do not require a CRN because they are not incorporated and are not required to file their statutory records with Companies House. Types of business not requiring a CRN include sole traders and general partnerships.

You may hear a company registration number being referred to as a ‘Companies House number’ or just ‘company number’.

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A CRN (company registration number) is a unique code that Companies House uses to help it quickly and correctly identify a company.

A company registration number remains the same for the life of the company. It will be the principal way Companies House identifies a company regardless of any changes of name, address, directors, shareholders, or business activities. It is not possible to choose or reserve a particular company registration number; it is computer-generated and assigned automatically upon incorporation.

What is the format of the company registration number?

CRNs are always 8 characters long. These can be either 8 digits or 2 letters followed by 6 digits.

  • English and Welsh companies have 8-digit CRNs beginning with 0 or 1.
  • Scottish companies have CRNs with the letters ‘SC’ followed by 6 digits.
  • Limited liability partnerships (LLPs) have the letters ‘OC’ followed by 6 digits.
  • Scottish LLPs have the letters ‘SO’ followed by 6 digits.
  • Northern Irish companies have the letters ‘NI’ followed by 6 digits.
  • Northern Irish LLPs have the letters ‘NC’ followed by 6 digits.
Company registration number examples CRN

Some older Northern Irish companies have CRNs with the letter ‘R’ followed by 7 digits, but these numbers are no longer issued.

Additionally one may encounter CRNs issued to the less common types of company, for example Royal Charter companies whose CRNs begin with the letters ‘RC.’ There are a few others that are very specialised and some historic ones that are no longer issued to new companies. One very rarely comes across these.

Your CRN is not to be confused with your …


  1. Unique taxpayer reference(UTR) – issued by HMRC, consists of 10 digits (e.g. 9012345678), used to identify a company for tax-related purposes.
  2. VAT number– issued by HMRC for companies registered for value added tax. It consists of 9 digits, with “GB” sometimes included as a prefix (e.g. GB123456789).
  3. Employer reference number (ERN)– issued by HMRC when an employer registers to operate PAYE (pay as you earn) for its employees. The first part of the reference is 3 digits, which identifies the tax office that deals with the company’s PAYE. The second part, following a forward slash, is the tax office’s employer reference. An example PAYE reference might be 123/CD678.
  4. Accounts Office Reference (AORN), a unique series of thirteen characters used by HMRC to link an employer’s PAYE payments to their online PAYE account. It is issued alongside an employer’s ERN (PAYE reference). The two references are easily confused as they often appear together on P45s, P60s, P11Ds and payslips. An AORN always starts with three digits followed by an uppercase P, e.g. 234PX0023456X.
  5. Companies House authentication code, a 6-character alphanumeric code provided by Companies House upon registration. It allows you to access the WebFiling system and make changes to your company records. It will be something like A1BC2D.

How Companies House uses your CRN for WebFiling

A company’s CRN is appended to Companies House’s web gateway address thus: data.companieshouse.gov.uk/doc/company/{companynumber}. That web address is known as a URI (Uniform Resource Identifier). It defines the location where the company’s data is stored at Companies House. When queried it returns a summary of the company’s filings.

Inform Direct company secretarial software uses this data location to update a company’s filings when customers manage their company books via Inform Direct’s improved interface and document management tools.


Where can I find my company registration number?

You can find your company registration number in multiple places:

  1. On the company’s certificate of incorporation.
  2. On any official letters or other documentation received from Companies House.
  3. If using Inform Direct, your CRN appears on your Company Information screen and in the ‘Company Number’ column on the organisation list.
  4. On the public register. You can search Companies House records by company name.
  5. In emails or other correspondence from your company formation agent or accountant. If an accountant or formation agent formed the company for you, they may well have quoted the company number when sending you the initial documents relating to the company.
  6. On a change of company name certificate. If you have changed your company name, you will have received a change of company name certificate from Companies House. Just like with the certificate of incorporation, both the company name and company registration number are shown prominently on the certificate.
Company registration number examples CRN

When do I need to use my company registration number?


It needs to be quoted in most correspondence with Companies House and when changing company records including:

Your CRN must also be quoted in certain dealings with HMRC, including:

You may also be expected to give your CRN in other circumstances, including when:

Where must the company registration number be displayed?

The law requires a limited company or LLP to display its company registration number on its website (it most commonly appears in the footer), on its company stationery and on business documents such as invoices.

All companies are required to maintain up to date company records. Inform Direct is the perfect tool to help you easily keep everything up to date.

This article was originally published in 2015. It was thoroughly revised and updated in August 2022.

Article Comments

  1. George Ferzoco says:

    Well written, thank you!

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