UK company registration number (CRN): format, prefixes and how to verify one

Every UK limited company has one — an 8-character company registration number (CRN) issued by Companies House the moment the company is incorporated. It is the single piece of identification that never changes, and it is the one detail you should insist on before signing a contract, paying an invoice or onboarding a supplier. A trading name can be reused, an address can be shared with a hundred other shells, but a CRN maps to exactly one legal entity.

This guide covers what a CRN actually is, how to read it, where to find and verify one, and the practical checks to run once you have it. If you just want the tool, jump straight to our free company number lookup — no signup required.

What is a UK company registration number?

A CRN is the unique identifier Companies House assigns to every company incorporated in the UK. It appears on the certificate of incorporation, on every filing the company makes, and — by law — on the company's letterheads, invoices, order forms, emails and website. Under section 82 of the Companies Act 2006 and the Companies (Trading Disclosures) Regulations 2008, a UK limited company that omits its CRN from these disclosures is committing an offence, and the directors can be fined.

The number is fixed. If a company changes its name, its directors, its registered office or even its share capital, the CRN stays the same for the entire life of the company. That permanence is what makes it useful as a compliance anchor.

What a CRN is not

• Not a VAT number. VAT numbers are 9 digits, issued by HMRC, and only apply to VAT-registered businesses. Plenty of legitimate small companies never register for VAT.
• Not a UTR. The Unique Taxpayer Reference is a 10-digit number HMRC uses for corporation tax. It is private and should never appear on a supplier's invoice.
• Not proof of trading. A CRN only proves a company exists on the register. It says nothing about whether the company is solvent, active or trading. That is what the rest of a proper due-diligence workflow is for.

How to read a UK company registration number

Standard English and Welsh CRNs are 8 digits, zero-padded. So company number 4871687 is really 04871687 — a common trap when copying CRNs out of PDFs or spreadsheets that strip leading zeros. Companies House accepts both the padded and un-padded form in search, but the canonical record uses the 8-character version.

Scottish, Northern Irish and specialist entity types use two-letter prefixes. The prefix tells you both where the company is registered and what kind of entity it is:

• No prefix (8 digits): Limited company registered in England and Wales.
• SC: Registered in Scotland (e.g. SC123456).
• NI: Registered in Northern Ireland.
• OC / SO / NC: Limited liability partnership in England and Wales, Scotland, Northern Ireland respectively.
• LP / SL / NL: Limited partnership in the same three jurisdictions.
• RC / SR / NR: Royal Charter, Scottish charity or Northern Irish equivalent — rare in commercial contexts.
• FC / SF / NF: Overseas company registered as a UK establishment.

The prefix matters because the applicable law changes with it. A Scottish LLP is governed by Scots law and files at Companies House Edinburgh; the same is not true for an English LLP. If you are drafting a contract or serving a statutory demand, the prefix is where you check first.

Formatting quirks that trip people up

Two edge cases are worth knowing. First, historically-old companies sometimes have shorter numbers on paper (e.g. six digits) because the certificate was issued before Companies House standardised on 8-character CRNs. The current record on the register will always be zero-padded to 8 characters. Second, dissolved companies keep their CRN; the number is never re-used. If someone hands you an invoice quoting a CRN that resolves to a dissolved company, that is not a coincidence to explain away — it is the entire story.

Where to find a company registration number

You should not have to hunt for a CRN. Legitimate UK companies publish theirs voluntarily and prominently. The four places to look, in order:

1. The company's own website. Almost always in the footer, on the "Contact us" page, or in the site's terms and conditions. Trading disclosure regulations require it.
2. Invoices, quotes and order forms. Same rules apply. If a supplier's invoice omits the CRN and registered office, that alone is a red flag worth chasing before you pay.
3. Email footers. Legally required on business correspondence sent by a UK limited company. It is a light check — a missing CRN could just be an oversight — but combined with other signals it starts to matter.
4. Companies House search. If none of the above yields a number, search by name at Companies House or run our free lookup tool which handles the name-to-CRN mapping in one step.

When a company name matches more than one CRN

Two common patterns cause this. First, companies routinely trade under a name that differs from their registered name — a coffee shop called "Beans & Books" might be registered as "MJH Hospitality Ltd". Trading names are not registered anywhere; only the legal name is. Second, the same registered name can occasionally appear across separate jurisdictions (an English and a Scottish "XYZ Consulting Limited"), or the register may contain a dissolved company plus a new one with the same name. Always compare the registered office, the incorporation date and the directors before you commit to a CRN.

How to verify a CRN is real (and matches the trader in front of you)

Having a CRN is the start, not the end. The verification workflow we recommend for finance, procurement and compliance teams runs in four steps.

Step 1: Confirm the CRN resolves and is active

Look up the CRN. Check the "Company status" field on the Companies House record. You want to see "Active". Statuses that should stop the workflow include:

• Dissolved — the company legally no longer exists. It cannot enter into contracts, and any invoice it raises is not enforceable against it.
• Liquidation or In administration — creditors are being managed by an insolvency practitioner. Any new trading is either paused or being wound down.
• Proposal to strike off — Companies House intends to remove the company from the register, usually because filings are overdue. Not immediately fatal, but investigate before proceeding.

Step 2: Match the entity to the person on the other side

Confirm the registered office, incorporation date and directors on the Companies House record are consistent with what the counterparty has told you. Mismatches are common with fraud attempts: the CRN is real but points to a legitimate company being impersonated. If your supplier's email domain and website don't line up with the registered name — for instance, "Global Supplies UK" invoicing from @globalsupplies-uk.net while the CRN resolves to "Zenith Fulfilment Ltd" incorporated last week — that is the whole flag.

Step 3: Check filings, PSCs and charges

A company that has failed to file confirmation statements or accounts for over a year is either dormant, in trouble, or something more concerning. The Persons with Significant Control (PSC) record tells you who ultimately owns and controls the entity — we cover this in depth in our post on Persons of Significant Control. Outstanding charges (mortgages, floating charges, debentures) show which lenders have prior claims on the company's assets.

Step 4: Screen for adverse signals

Finally, run the company name and its directors through sanctions and PEP watchlists, and do a quick sweep of recent news for insolvency, fraud, disputes or enforcement action. This is where "checking a CRN" tips over into full due diligence. For a walkthrough, see our complete guide to UK company due diligence, and if you're specifically worried about repeated director insolvencies, our post on spotting a phoenix company.

Common CRN mistakes we see

Three patterns come up again and again in the checks that go wrong:

1. Assuming a CRN means "verified". A CRN only proves incorporation, and incorporation in the UK costs £50 and takes an afternoon. Fraud-oriented shell companies have CRNs too. The CRN is your starting point, not your conclusion.
2. Ignoring the leading zero. If your accounting system stripped a leading zero and your check returned a "not found", the company probably does exist — pad to 8 digits and try again. This is a particular hazard when copying CRNs out of Excel.
3. Not distinguishing the trading name from the registered name. "Sold you by" and "invoiced you by" are often different in a legitimate group structure. Ask which specific legal entity you are contracting with, and get the CRN for that entity, not the parent brand.

Frequently asked questions

Is a UK company registration number confidential?

No. CRNs are public data. Companies House publishes them, and companies are legally required to display them. Treating a CRN as sensitive is a category error — it is closer to a postal address than a national insurance number.

Can two companies share a CRN?

Never. Each CRN maps to exactly one company, alive or dissolved, forever. If you find two records with the same number, one is a data-entry error somewhere upstream.

What if a supplier refuses to give me their CRN?

Treat this as a hard stop. UK trading regulations require them to disclose it on any invoice, quote or order form. A refusal is either a fraud signal or an operational chaos signal, and neither is a good reason to send money.

Does an overseas company have a CRN?

Only if it has registered a UK establishment, in which case it gets an "FC" (foreign company) prefix. A purely foreign trader dealing with you across borders will not have a CRN — you'll need to verify it against its home country's register instead.

Where to go next

If you just need to resolve a CRN to a company (or a company name to a CRN), the free company number lookup does the job in a couple of seconds — no account needed. If you're onboarding a new supplier or customer and want the full picture — status, filings, directors, PSCs, charges, watchlists and recent news — sign up for a free CompanyCheckr account and run a full report. And if you want to see exactly how we combine these signals into a risk view, our methodology page lays it out end to end.

Whatever you do next, don't stop at the CRN. It's the door, not the room.