How to check if a UK company is legitimate

Someone sends you a quote on headed paper. The logo looks professional, the email address matches the domain, and the company number at the bottom of the invoice has eight digits. On paper – literally – everything checks out.

Most UK counterparty deception hides behind exactly this kind of surface. The company exists. The filings are up to date. The director has a LinkedIn. What's missing is the one or two data points that would have told you to pause: a dormant trading history, a director who controls eleven other dissolved companies, or an address that's a mail-forwarding service in Belgravia.

This guide walks through the checks that actually catch problems. None of them require specialist tools – everything here is built on Companies House public data. At the end we show how B2Verify automates the whole thing into a single lookup.

1. Start with the company number

Every UK limited company has an eight-character Companies House number (for example, 12345678). It's the one piece of identity you should never skip. Ask for it before you do anything else – by email, in the onboarding form, or printed on the quote.

If the company cannot produce a number, or gives you one that looks malformed, stop. Spoofed invoices often use realistic-looking but invalid numbers, banking on the recipient not checking.

Companies House numbers have a few valid formats:

• England and Wales: 8 digits, e.g. 12345678
• Scotland: SC + 6 digits
• Northern Ireland: NI + 6 digits
• Limited Liability Partnerships (England and Wales): OC + 6 digits
• Limited partnerships: LP + 6 digits
• Overseas entities: OE + 6 digits

Numbers with SO (Scottish LLP), NC (Northern Ireland LLP) or FC (overseas company with a UK establishment) are also valid Companies House numbers – see the dedicated number lookup guide for the full reference. Anything that doesn't match one of these formats is either a trading name (not a legal entity) or fabricated – treat the latter as warrants written verification before payment until proven otherwise.

2. Check the company is active, not dormant

Not every company on the register is actually trading. Three statuses matter to you as a counterparty:

• Active: the company has filed its last confirmation statement on time and is legally trading.
• Active – Proposal to Strike Off: someone has started to close the company. Do not transact – once struck off, the company ceases to exist, and any money in its name becomes property of the Crown.
• Dormant: the company is registered but reports no significant accounting transactions. A long dormant history before suddenly "re-activating" is a recurring incorporation pattern.

You can read the status directly on the Companies House overview page, or use B2Verify's search which surfaces the same information alongside a risk rating.

3. Read the last confirmation statement

A confirmation statement is the annual filing that tells Companies House the basic facts about a company are still correct – registered office, directors, shareholders, people with significant control (PSCs), SIC codes.

Two things to check:

Is it up to date? Every UK company must file one within 14 days of the anniversary of its incorporation or previous statement. If it's overdue, the company is in breach – and companies in breach are the first to be struck off.

Does it match what you're being told? If the quote says the company has twenty staff and trades as a software house, but the latest confirmation statement lists one director, no employees and a SIC code for "Retail sale via mail order houses or via Internet," something is wrong.

4. Look at the filing history – especially accounts

Accounts are the single richest public document about a UK company. For small companies, filings are abbreviated (a balance sheet, nothing more), but even the minimum tells you:

• Whether the company has any assets at all
• Whether it has traded in the last year
• Whether its net position is positive or negative
• How late the last accounts were filed

A company that's on its third consecutive extension and has filed nothing but micro-entity dormant accounts for five years is not the twenty-staff software house it claims to be.

On the filing history page, look for:

• AA – annual accounts
• CS01 – confirmation statement
• AP01 / TM01 – appointing or terminating a director
• GAZ1 / GAZ2 – gazette notices of proposed and final strike-off

Multiple GAZ notices in the last two years means the company has flirted with dissolution. That is not automatically disqualifying, but it's worth asking about.

5. Check the directors and PSCs

The people running the company matter as much as the company itself. Two questions to ask of every director and person with significant control:

How many other companies do they run? A director with one or two other appointments is normal. A director with forty appointments across the last decade, most of them dissolved, is a serial incorporator – possibly legitimate, but far more often a director associated with the recurring incorporation pattern or a nominee.

Have any of those companies been struck off or liquidated? Companies House shows each director's full appointment history. Patterns of incorporation → short trading → compulsory strike-off → new incorporation are the pattern that warrants recurring incorporation pattern.

On B2Verify, clicking a director's name on any company page shows every UK appointment they've ever had – active and resigned – so this check takes seconds rather than half an hour. The walkthrough of a sample report shows exactly where on the page this lives.

6. Verify the registered office

The registered office is the legal address of the company, not necessarily where it trades. That's fine – plenty of legitimate businesses use an accountant's or a serviced-office address.

The red flag is when every piece of a company's identity points to a mail-forwarding service and there's nothing else: no real trading address, no staff, no website, no telephone number. You are almost certainly looking at a letterbox company.

A quick Companies House search on the registered office address itself will show you how many other companies share it. A mainstream accountant's address will have thousands. A rented-out virtual office with 200 companies and a suspicious cluster of dissolutions is a warning.

7. Run the whole thing in one click

Steps 1 – 6 are free and public. They will also take you the better part of an hour for a single company if you do them properly. For any business that verifies more than a handful of counterparties a year, that time adds up fast.

B2Verify collapses the same workflow into a single lookup:

• Enter a company number or name on the search page
• See the full Companies House record, filing history and director network in one view
• Read a Trust Score from 0 – 100 that aggregates the signals above into one number, with the reasons behind it
• Optionally add the company to your monitored list to get an email the moment anything changes (new filing, status change, director turnover)

The underlying data is the same public data you can get from Companies House. The difference is that B2Verify has already done the cross-referencing – director networks, filing patterns, dissolution history – and flagged the parts that matter.

When to walk away

If any of the following is true, do not transact without further investigation – usually a signed contract, upfront deposit, or escrow arrangement:

• The company is Active – Proposal to Strike Off
• The last confirmation statement is more than six months overdue
• Accounts have been dormant for the company's entire history and the quote implies active trading
• The director has a pattern of short-lived dissolved companies
• The registered office is shared with dozens of dormant or dissolved companies
• The company number the other party gave you does not match the name on their quote

None of these are individually proof of wrongdoing. All of them are signals that the story you've been told is not the story on the register – and that's always worth a conversation before money moves.

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Ready to check a company? Search B2Verify – it's free to look up any UK business, and the Trust Score surfaces everything in this guide in one view.