A company name can change, be misspelt, be shared by a dormant company in another jurisdiction, or be almost identical to a competitor's. A company number cannot. It is assigned by Companies House at incorporation, it is unique, and it stays with the company until it is dissolved. If you do any kind of company research, the number is the key you should store.
The format
Every company registration number is eight characters. For companies registered in England and Wales it is eight digits, and because numbers are issued sequentially, newer companies have higher numbers: a company incorporated in 2026 will typically start with 16 or 17. Older companies were issued shorter numbers that are now shown padded with leading zeros, which is why you will see numbers like 00123456 for companies formed decades ago.
For everything else, the first two characters are letters that tell you the jurisdiction or the type of entity.
| Prefix | Meaning |
|---|---|
| (digits) | Company registered in England and Wales |
| SC | Company registered in Scotland |
| NI | Company registered in Northern Ireland (older NI companies may use R) |
| OC | Limited liability partnership, England and Wales |
| SO | Limited liability partnership, Scotland |
| NC | Limited liability partnership, Northern Ireland |
| LP | Limited partnership, England and Wales |
| SL | Limited partnership, Scotland |
| FC | Overseas company with a UK establishment |
| BR | UK establishment (branch) of an overseas company |
| RC | Royal charter company |
| CE | Charitable incorporated organisation |
Company Signal shows the number on every profile and uses it in the page URL, so a company can always be found again even after a name change.
Where to find it
The number appears on the certificate of incorporation, on the Companies House register, and by law on a company's website, business letters and emails alongside its registered office address. If you only have a name, search it on the Companies House service or on Company Signal; if several companies share the name, the incorporation date and registered office will tell them apart.
What it is not
- It is not the VAT number, which is issued by HMRC, has nine digits and is only held by VAT-registered businesses.
- It is not the Unique Taxpayer Reference (UTR), a ten-digit HMRC identifier used for corporation tax.
- It is not a charity number, which is issued by the Charity Commission or its Scottish and Northern Irish equivalents. A charitable company has both.
- It is not proof that a company is trading. A number confirms registration; the company may be dormant, or may never have started.
Using the number in research
Store the company number as the primary key in your CRM or spreadsheet, and use it in API calls rather than name searches. The Companies House API resolves a number to a profile, its officers, its people with significant control, its filing history and its charges. Company Signal does the same: search a number and you land on the full profile with an AI brief.
QUICK ANSWERS
Questions this article answers
- How long is a UK company number?
- Eight characters. Companies registered in England and Wales have eight digits, usually starting with 0 or 1. Companies registered elsewhere or of other types have a two-letter prefix followed by six digits, such as SC for Scotland or NI for Northern Ireland.
- Can a company number change?
- No. A company number is assigned at incorporation and stays with the company for life, even if it changes its name, address or type. Two companies can never share a number.