Companies House data for lead generation: what it gives you, and what it leaves out

Companies House data is the best free starting point for UK lead generation and, on its own, a poor finishing point. It tells you that a company exists, what it says it does, who runs it and which dates are coming up. It does not tell you how to reach anyone. Everything useful about using it for leads follows from holding those two facts together.

This page sets out what the public record holds, the three ways to get it, what it leaves out, and what closing that gap involves. The film above shows the end result: a lead that started as a filing and arrives with a person, a tested address and a first line.

What the public record holds

Every UK limited company and LLP must file with Companies House, and what they file is public. On 19 September 2026 that was just under six million live companies. For each one you can read:

• Identity. Name, company number, status and the date it was registered.
• Trade. Up to four SIC codes, chosen by the company to describe its work.
• Address. The registered office, which for small firms is often their accountant's address.
• People. Directors and secretaries, with appointment dates, and the people with significant control.
• Dates. When the next accounts and the next confirmation statement are due, and whether either is late.
• History. Every filing made, plus any charges registered against the company.

Two of those are worth far more than the others for finding customers. The trade codes let you narrow six million companies to the few thousand in your market, and the complete guide to SIC codes shows how. The dates tell you when.

What it leaves out

The public record has never held an email address, a phone number or a website. That is not an oversight to be worked around with a cleverer query. The data is not there.

It also says less about size than people expect. Small companies can file accounts without a profit and loss account, so turnover is missing for most of the firms a small business would sell to. And the registered office is a legal address, not necessarily where anybody works.

So a list built only from Companies House is a list of true facts about companies you cannot contact. Any dataset that does offer contact details has added its own layer on top, and the right question for any supplier is how that layer was built and how it was checked.

Three ways to get the data

All three are free, and they suit different jobs:

1. The website and its advanced search. Filter by SIC code, registration date, status and location, then download the results. Good for a one-off list and for checking a single company.
2. The bulk download. A monthly snapshot of every live company. Good for a first load into your own database.
3. The API and the streaming service. Look companies up on demand, or receive changes as they are filed. The API allows 600 requests every five minutes per key.

Most serious users end up combining them. The Companies House API, explained covers keys, limits and the gotchas, and when the official API is not enough covers the point where building it yourself stops being worth it.

The dates are the useful part

A trade code tells you who a company is. A date tells you why to write this week, and that is what turns a list into outreach somebody answers.

The reasons we read from the public record today are these:

• Just incorporated. A new company chooses its bank, insurer, accountant and suppliers once.
• Accounts due, or overdue. Somebody has to file them, and the decision is made weeks before the date.
• Confirmation statement due, or overdue. A small unavoidable job, and a fair first piece of work.
• First accounts coming. The moment a founder stops doing it themselves.

One further reason comes from the company's own website rather than its filings: a site our crawler has graded as poor, which is the opening a web designer needs.

Two honest limits. Deadline dates come from the monthly bulk file, so they can be up to a month behind the live record. And a company registered this month usually cannot be reached yet, so we hold it back until it can. UK company buying signals and how filing deadlines work go deeper on each.

The gap between a filing and a lead

Four things have to happen before a filing is worth an email, and the numbers shrink at every step:

1. Match. The company fits your trade codes, your area and your reason.
2. Find the person and the site. A named director, and a website that is really theirs.
3. Check the address. An email address tested before anything is sent to it, not guessed from a pattern.
4. Write the first line. One sentence, specific to that company, from what the filing says.

A company that fails any check is not a lead. In our own product it is held back and never charged for, so there is nothing to refund. Turning Companies House rows into contactable leads describes the enrichment step in detail, and why filing-traced data beats scraped profiles explains why we start from filings rather than scraped profiles.

Can you use Companies House data for marketing?

The company data, yes. It is public information, and the usual courtesy is to say where it came from, as we do on our data sources page.

The care is needed around people. A director's name is personal data, and so is a business email address that identifies a person, so writing to them needs a lawful basis. For relevant business-to-business email that is normally legitimate interest. Separately, UK marketing rules let you email a limited company without prior consent if you identify yourself and offer an opt-out, while sole traders and partnerships are treated as individuals.

Whether using UK business data is legal, what legitimate interest requires and whether a business email is personal data cover the detail. This is practical guidance, not legal advice.

What it looks like with the gap closed

In the film, a kitchen fitter types one sentence: he fits kitchens for builders around Stockport. That becomes a standing watch on the public record for newly registered building firms in his towns. Every morning at half past six it runs again without him.

What reaches him is not a row. It is a building firm, the director who runs it, the date it was registered, a website that has been opened and an email address that has been tested, with a first line already written from the filing. He changes what he likes and approves it, and it goes from his own mailbox under his own name. For a trade-by-trade version of the same idea, see how to get work from builders.

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