A UK registration number is a unique identifier assigned to a business or organisation by Companies House, the UK government body that records company information

Every limited company, limited liability partnership (LLP), and certain other business structures registered in the UK receives a registration number when they first register. This number stays with the organisation for life, even if the company name changes, moves location, or restructures. You will see it written as an eight-digit number — for example, 12345678.

The registration number is not the same as a tax reference number, VAT number, or PAYE reference. It is purely a Companies House identifier used to look up company records, check who owns or runs a business, and verify that an organisation is legally registered to operate.

Key Takeaways

  • A UK registration number is an eight-digit code issued by Companies House to every registered business, and it remains the same throughout the company's lifetime.
  • You can find a company's registration number by searching the Companies House register online for free, using the company name or postcode.
  • The registration number appears on official company documents including incorporation certificates, annual accounts, and correspondence from Companies House.
  • Registration numbers are public information — anyone can search for them to verify a business is real and to see details like directors, shareholders, and financial records.
  • Sole traders and partnerships do not receive registration numbers unless they choose to register as a limited company or LLP.

Where to find a registration number

The fastest way to find a company's registration number is to search the Companies House register online at companieshouse.gov.uk. The search is free and takes seconds. Type in the company name, and the register will show you the registration number along with the company's current address, directors, and filing history.

If you are looking for your own company's registration number and you have lost it, check any official paperwork from when the company was set up. Your incorporation certificate — the document you received when the company was first registered — displays the number prominently at the top. You will also find it on annual accounts filed with Companies House, on payroll documents, and in any correspondence from Companies House itself.

If you registered the company yourself online through Companies House, you can log back into your account and view the registration number there. The number also appears on your company's bank account paperwork and insurance documents.

What information is linked to a registration number

When you search for a registration number on the Companies House register, you can see a range of public information about that business. This includes the names and addresses of all current directors, details of any shareholders or members, the company's registered office address, and the date the company was incorporated.

You can also access the company's filed accounts (usually for the past three years), confirmation statements (annual updates to Companies House), and details of any charges or mortgages against company assets. For limited companies, you can see the company's Memorandum and Articles of Association — the rules that govern how it operates.

This information is public by law. Anyone can search it to check whether a business is legitimate, who runs it, and whether it is in good financial standing. Many people search registration numbers before doing business with a company or before investing money.

Registration numbers for different business types

Only certain business structures receive a registration number. Limited companies (Ltd) and limited liability partnerships (LLP) must register and receive a number. Private companies limited by may provide (often charities or not-for-profits) also register and receive a number.

Sole traders and traditional partnerships do not receive a registration number from Companies House unless they choose to incorporate as a limited company or LLP. If you run a business as a sole trader, you will have a tax reference number from HMRC instead, but not a Companies House registration number.

Charities registered with the Charity Commission have their own separate charity registration number, which is different from a Companies House registration number. Some charities are also registered at Companies House and have both numbers.

How registration numbers are structured

A UK registration number is always eight digits long. There is no hidden meaning in the digits — they are straightforward assigned sequentially as companies register. The first company registered at Companies House received 00000001, and numbers have been issued in order ever since. A lower number does not mean a company is older or more established; it straightforward means it registered earlier.

Registration numbers are sometimes written with leading zeros (00123456) and sometimes without (123456), but they refer to the same company. When you search the Companies House register, it will show you the number in its standard eight-digit format.

Why you might need to provide a registration number

You may need to provide your company's registration number when opening a business bank account, explore for credit or a loan, registering for VAT, or setting up payroll. Suppliers and customers may ask for it to verify your business is real and to check your company details.

If you are buying goods or services from a company, asking for their registration number and checking it on the Companies House register is a straightforward way to confirm they are a legitimate registered business. This is especially useful if you are considering a large purchase or transferring money.

Some online platforms and government services also ask for a registration number as part of their verification process. Having it to hand makes the process faster.

What happens if a company's registration number changes

A registration number does not change. Once a company is assigned a number, it keeps that number even if the company name changes, the directors change, or the registered office moves to a different address. The only time a registration number stops being used is if the company is struck off the register (dissolved) or removed by Companies House.

If a company is dissolved and then later restored to the register, it receives the same registration number it had before. This means the registration number is a permanent record of that legal entity.

Frequently Asked Questions

Can I search for a company using just its registration number?

Yes. On the Companies House website, you can search by registration number directly. Type the eight-digit number into the search box, and the company record will appear. This is often faster than searching by company name if you already have the number.

Is a registration number the same as a company number?

Yes, they are the same thing. Registration number, company number, and Companies House number all refer to the same eight-digit identifier. You will see these terms used interchangeably in official documents and on the Companies House website.

What if I search for a company and cannot find a registration number?

If a company does not appear in the Companies House register, it may be a sole trader, a partnership, or an unregistered business. It could also be registered in a different part of the UK (Scotland and Northern Ireland have separate registers), or it may not be a legitimate registered business at all. Ask the company directly for its registration number, or contact Companies House if you believe a business should be registered.

Do I need a registration number to start a business?

Only if you want to register as a limited company or LLP. If you operate as a sole trader or partnership, you do not need to register with Companies House and will not receive a registration number. You will still need to register for tax with HMRC.

Can registration numbers be reused?

No. Once a registration number is assigned, it is never reused, even after a company is dissolved. This ensures each number uniquely identifies one legal entity and prevents confusion in historical records.