Key takeaways
- A company registration number (CRN) is the unique 8-character number Companies House gives a company, LLP or limited partnership when it is registered.
- Companies registered in England and Wales usually have 8 digits; Scottish companies start with SC and Northern Irish companies with NI, followed by 6 digits.
- You can find any company's number free by searching its name on the Companies House service Find and update company information.
- Your own company number is printed on your certificate of incorporation and on every letter Companies House sends you.
- A company must show its registered number, registered office address and place of registration on its letters, order forms and website.
- The company number is not the same as the 10-digit Corporation Tax UTR from HMRC or the 6-character authentication code used to file online.
- Sole traders and ordinary partnerships are not registered at Companies House, so they do not have a company registration number.
A company registration number (CRN) is the unique 8-character number Companies House gives every company, limited liability partnership (LLP) and limited partnership when it joins the register. It never changes, even if the company changes its name or address. You can find any company’s number free on the Companies House register, and your own is on your certificate of incorporation.
What is a company registration number?
A company registration number is the permanent identifier for a company on the Companies House register. It is sometimes called a company number or CRN. The name can change; the number stays the same for the life of the company, including after it is dissolved.
Companies House prints the number on the certificate of incorporation, which states “the name and registered number of the company”. Banks, HMRC, suppliers and credit agencies use it to make sure they have the right company.
What does a company number look like?
Most company numbers are 8 digits, or 2 letters followed by 6 digits. The letters show where the business is registered and what type of entity it is.
| Number starts with | What it usually means |
|---|---|
| 8 digits (e.g. 01234567) | Company in England and Wales |
| SC | Company registered in Scotland |
| NI | Company registered in Northern Ireland |
| OC | LLP in England and Wales |
| SO | LLP in Scotland |
| NC | LLP in Northern Ireland |
| LP, SL, NL | Limited partnership (England and Wales, Scotland, Northern Ireland) |
Leading zeros matter. A number written as 1234567 is usually 01234567 on the register. Type it in capitals with no spaces and no “GB” in front.
Companies House uses other, rarer prefixes for older and overseas entities. If you see one you do not recognise, check the company’s page on the register rather than guessing.
How do you find a company’s registration number?
You can look up any UK company’s number free in under a minute.
- Go to Find and update company information.
- Type the company name in the search box.
- Pick the right company from the list; check the registered office address if several names are similar.
- The company number appears under the name, at the top of the company overview page.
The same page shows the incorporation date, directors, filing history and status. Our guide on how to look up a company on Companies House explains what else you can check.
Where to find your own company number
Your own company number is on almost every document Companies House sends you. Check these first:
- your certificate of incorporation
- letters and emails from Companies House, including authentication code letters
- your filed accounts and confirmation statement
- your company’s page on the Companies House register
- your business bank account documents and HMRC Corporation Tax letters
If you need a fresh copy of the certificate, Companies House charges £22 by post, or £65 for same-day service, according to its fees page updated 25 September 2026.
Where must you show your company number?
A limited company must show its registered number on its letters, order forms and website. GOV.UK’s guidance on signs, stationery and promotional material says these must also show:
- the registered office address
- where the company is registered (England and Wales, Scotland or Northern Ireland)
- that it is a limited company, usually by giving the full name including “Limited” or “Ltd”
Most companies put these details in their email signature and website footer too. Invoices have their own rules; see our guide to invoice number rules.
Company number vs UTR vs authentication code
These three numbers are often confused, but each does a different job.
| Number | Issued by | Used for |
|---|---|---|
| Company number (8 characters) | Companies House | Identifying the company on the public register |
| Corporation Tax UTR (10 digits) | HMRC | Corporation Tax returns and payments |
| Authentication code (6 characters) | Companies House | Filing online; works like an officer’s signature |
The company number is public. Keep the UTR and the authentication code private, because they are used to file on the company’s behalf. HMRC posts the UTR to the registered office after incorporation; you can request it again through the find your UTR service. Our guide to UK tax identification numbers covers VAT and PAYE references too.
Which businesses have a company number?
Only businesses on the Companies House register have one. Use this check:
- If you run a private or public limited company, you have a company number.
- If you run an LLP or a limited partnership, you have one, starting with letters such as OC or LP.
- If you are a sole trader, you do not; HMRC gives you a UTR instead.
- If you are in an ordinary partnership, you do not, because it is not registered at Companies House.
Thinking of incorporating? See how to set up a limited company.
Frequently asked questions
How many digits is a UK company registration number?
It has 8 characters. Companies in England and Wales usually have 8 digits; Scottish and Northern Irish companies have 2 letters (SC or NI) followed by 6 digits.
Is a company registration number the same as a VAT number?
No. The company number comes from Companies House; a VAT registration number comes from HMRC when the business registers for VAT. You can check a VAT number with our guide to checking a VAT number.
Can a company number change?
No. A company keeps the same number for its whole life, even if it changes its name or registered office.
Does a sole trader have a company registration number?
No. Sole traders are not registered at Companies House, so they have a UTR from HMRC but no company number.
Is it free to look up a company number?
Yes. Searching the Companies House register and viewing a company’s details and filed documents is free.
Do I have to put my company number on my website?
Yes. GOV.UK says a limited company must show its registered number, registered office and place of registration on its website, letters and order forms.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.