- What is a company registration number?
- Who needs a CRN?
- What does a company registration number look like?
- 5 ways to find your company registration number
- Where you must display your company registration number
- CRN vs. other UK business identifiers
- Ramp puts your invoices through one workflow, now in the UK
A company registration number (CRN) is the unique 8-character code Companies House assigns to every incorporated business in the UK at the moment it registers. It's the legal identifier that proves your business exists, and it stays with the company for its entire life, even if you change the name, the registered office, or the directors.
If you run a UK limited company or a limited liability partnership, you already have a CRN whether you've looked for it or not. The law also requires you to display it on your business letters, order forms, and website, with fines for failing to do so.
This guide is general information, not legal or tax advice. Companies House and GOV.UK are the authoritative sources for registration requirements, and rules can change. Check with your accountant or solicitor if you're unsure what applies to your company.
What is a company registration number?
A company registration number is the unique identifier Companies House issues to a business at incorporation. It's often shortened to CRN or referred to as a Companies House number or company number. Every incorporated business in the UK receives one automatically as part of the registration process, and the number is generated by Companies House rather than chosen by the company.
The CRN serves as your company's official legal identity in dealings with government bodies, banks, customers, and suppliers. When HMRC, your bank, or a prospective supplier needs to confirm your business exists as a legal entity, they use the CRN to look you up on the Companies House public register.
The CRN is permanent. Once assigned, it stays with the company forever. A change of company name, registered office, directors, or share structure has no effect on the number. That permanence makes the CRN a more reliable identifier than the company name itself, which can change.
Who needs a CRN?
Only incorporated business types receive a CRN.
Businesses that receive a CRN:
- Private limited companies (Ltd)
- Public limited companies (PLC)
- Limited liability partnerships (LLPs)
- Limited partnerships (LPs)
- Community interest companies (CICs)
- Companies limited by guarantee (often used by charities and non-profits)
Businesses that do not receive a CRN:
- Sole traders
- General (unlimited) partnerships
- Unincorporated associations
- Trusts
Sole traders and general partnerships aren't registered with Companies House, so no CRN gets issued. They register with HMRC for tax purposes instead and receive a Unique Taxpayer Reference (UTR), which isn't a substitute for a CRN in any context where a CRN is required.
If you're a sole trader and a bank or client asks for your CRN, the answer is that sole traders don't have one. If you're a limited company and can't find yours, it exists and you can look it up on the Companies House register.
What does a company registration number look like?
CRNs are eight characters long, and the format indicates where the business is registered inside the UK.
| Where the business is registered | Company format | LLP format |
|---|---|---|
| England and Wales | 8 digits (e.g., 01234567 or 14235678) | OC followed by 6 digits (e.g., OC123456) |
| Scotland | SC followed by 6 digits (e.g., SC123456) | SO followed by 6 digits (e.g., SO123456) |
| Northern Ireland | NI followed by 6 digits (e.g., NI123456) | NC followed by 6 digits (e.g., NC123456) |
Limited partnerships are a separate entity type with their own prefixes. LP followed by 6 digits in England and Wales (e.g., LP123456), and SL followed by 6 digits in Scotland (e.g., SL123456).
Companies House has worked through several numbering ranges over the decades, so the leading digits tell you roughly when a company was incorporated rather than anything about its type.
Older numbers begin with zeros, and those zeros are often dropped in everyday use, so 644831 and 00644831 are the same company. The full form pads to eight characters. Community interest companies use the same format as ordinary limited companies, so the number alone won't tell you a business is a CIC.
5 ways to find your company registration number
1. The Companies House online register
Go to the Find and update company information service on GOV.UK, type your company name into the search bar, and select the correct entity from the results. The CRN appears at the top of the company profile page. This method works for any incorporated business, and the register is publicly accessible with no login required.
2. Your certificate of incorporation
The certificate of incorporation is the legal document Companies House issues when a business is first registered. Your CRN is printed at the top, alongside the registered company name and the date of incorporation.
If you've lost your certificate, Companies House can issue a certified copy for a fee, though the number on the public register is authoritative either way.
3. Your invoices, letterheads, or website footer
UK law requires limited companies and LLPs to display their CRN on official business communications. Your own invoices, letterheads, and website footer already carry the number.
4. HMRC and Companies House correspondence
Any letter from HMRC or Companies House references your CRN in the header or reference block. Tax correspondence, confirmation statement reminders, and filing notices all carry the number.
5. Your business bank paperwork or accountant
Your business bank account setup paperwork lists your CRN as part of the KYC record. Your accountant or company formation agent will also have the number on file.
Where you must display your company registration number
UK law requires limited companies and LLPs to display their CRN in specific places. The rules come from the Companies Act 2006 and The Company, Limited Liability Partnership and Business (Names and Trading Disclosures) Regulations 2015.
Places you must display your CRN:
- Business letters and official stationery, paper or electronic
- Order forms
- Invoices
- Your company website
- Business emails
The rules name business letters, order forms, and websites. Whether something counts as a business letter depends on its content rather than its format, so invoices and business emails generally fall inside the requirement, too. This is why most companies put the CRN in the email footer and on the invoice template once and leave it there.
The CRN isn't the only detail required on these documents. You also need the part of the UK where the company is registered and the address of the registered office. Your registered name has to appear alongside them, and everything must be legible.
Penalties for non-compliance:
Failing to make the required disclosures is an offence under the 2015 Regulations, which were made under section 82 of the Companies Act 2006. The fine can reach £1,000, with daily penalties of up to £100 while the non-compliance continues. The offence is committed by the company and by any officer in default.
If you trade under a different name from your registered company name, you still display the registered name and CRN on official documents. Dormant companies also retain their display obligations even if they aren't actively trading.
CRN vs. other UK business identifiers
Businesses accumulate identifiers, and the CRN is one of several numbers you may be asked to provide.
- Company registration number (CRN): Companies House assigns it at incorporation and is 8 characters and public
- Unique Taxpayer Reference (UTR): HMRC assigns it for corporation tax and is 10 digits and private
- VAT registration number: HMRC assigns it at VAT registration. It's 9 digits, written with a GB prefix for international use, and only VAT-registered businesses have one
- PAYE reference (ERN): HMRC assigns it when the business registers as an employer and only companies with employees have one
- Authentication code: A 6-character code Companies House uses to authenticate online filings which is kept confidential
The most common mix up is between the CRN and the UTR. The CRN is your legal identity at Companies House while the UTR is your tax identity at HMRC. They're issued by different bodies and serve different purposes.
Ramp puts your invoices through one workflow, now in the UK
Your company registration number follows your business everywhere. It sits on incorporation documents, invoices, supplier contracts, and the KYB checks that come with any financial product you apply for. Getting it right on outgoing paperwork is straightforward, but the harder part is what happens to the paperwork coming in.
For most finance teams that means using a UK corporate card that enables invoices to arrive by email, approvals stalling, receipts chased through Slack, and someone re-keying it all into Xero at month-end.
Ramp takes the invoice from the inbox, codes it, checks it against your policy, and routes it to the right approver with the audit trail intact. VAT is captured and coded for review before anything syncs to Xero or QuickBooks Online.
Ramp is currently in beta for UK-headquartered businesses.
Sign up for early access for Ramp in the United Kingdom.
This guide is general information, not legal or tax advice. Companies House and GOV.UK are the authoritative sources for registration requirements, and rules can change. Check with your accountant or solicitor if you're unsure what applies to your company.
“Invoices, cards, tokens. The categories change but the principle doesn't: know where the money is going, remove the work around it, and make sure the spend is worth it.”
Maciej Mylik. Finance
ElevenLabs
“There's just no surprises anymore. No more waiting two months to find out how a job did. We know how it's doing as it's happening.”
Erich Kuss
Financial Systems Manager, Infinity Home Services
“More token spend isn’t proof that AI is working. Less isn’t proof that it isn’t. What matters is whether we’re buying the right level of intelligence for the work. Ramp lets us make that judgment in the same place we manage every other type of spend.”
Cody Nutt
Senior Director of Business Systems, Daxko
“Most banks treat the back office as a cost to keep down. We treat ours as a return to compound, which is why we run it on Ramp. Now we put our clients on Ramp, too.”
Patrick Gaughen
President & COO, Hingham Institution for Savings
“Browserbase builds infrastructure so AI agents can do real work. Ramp is doing the same for finance. It’s not another tool. It’s a system purpose-built for AI-driven finance, and that’s why we chose Ramp as our financial operating system from day one.”
Paul Klein IV
Founder & CEO, Browserbase
“We used to pay up to $20k a year for our AP platform. With Ramp, we’re earning back well over that amount. That's money that belongs to the mission now, not to the back-office software.”
Heidi Coffer
Chief Financial Officer, Boys & Girls Clubs of San Francisco
“The tricky thing about corporate travel policy is timing. We didn't need a stricter policy. We needed the policy to show up earlier. With Ramp Travel, it finally does.”
Keith Frantz
Director of Enterprise Risk Management, Prosper
“We're accountable to our funders, our partners, and the families we serve. That accountability starts with how we manage every dollar. Ramp makes it easy for our team to spend wisely, track in real time, and keep overhead low so more resources reach the families navigating infertility.”
Rachel Fruchtman
CFO, Jewish Fertility Foundation
