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Companies House as a Lead Source (The Free Goldmine)

UK's Companies House holds current records on every registered business. Here's how to use it for B2B lead discovery.

Marius Nicola · · 5 min read

Companies House is the UK’s free, public register of every limited company, LLP, and community-interest company. It updates within 24 hours of filing. Most UK B2B lead-gen tools ignore it because they were built for the US market. That’s a gift if you know where to look.

What’s in it

  • Company name, number, registered address, incorporation date
  • SIC codes (industry classification)
  • Directors (name, DOB month/year, appointed/resigned dates)
  • Accounts: turnover, balance sheet, employees (for small+ filers)
  • Confirmation statements (annual)
  • Insolvency, strike-off, and administration notices
  • Share filings and charges

Why it’s better than paid databases

Apollo and Lusha sell static snapshots that go stale in weeks. Companies House updates every day. A director change that happened on Monday is visible to you on Tuesday. A company that crossed the £632K micro-entity threshold last quarter is flagged in its confirmation statement.

Practical ways to use it

  • ICP filtering. Filter by SIC code cluster (e.g. 62xxx for software) + turnover band to get a realistic target list.
  • Intent proxies. Recent director hires, SIC code changes, and sudden turnover jumps signal growth. Insolvency or mass-director-resignation signal churn (avoid).
  • Verification. Spot-check self-declared revenue against last-filed accounts. Mis-declaration above 10% is a red flag.
  • Enrichment. Pair Companies House registered address with a LinkedIn search for the CEO/founder named in filings.

Filings worth watching closely

Not every Companies House filing is equally informative. The ones that repay careful attention for lead generation:

  • Confirmation statements list current directors, PSCs (Persons with Significant Control), and SIC codes. File annually. Use them as your baseline truth on a company’s structure.
  • Director appointments and resignations (AP01, TM01). A new CFO is a different buying signal than a new non-executive director. Read the role, not just the event.
  • PSC changes (PSC01/02/03). New controlling shareholders almost always signal a deal, whether acquisition, investment, or restructure. Takeovers produce reliable integration spend.
  • Share-issuance filings (SH01). Capital has come in before the press release — often by weeks. An unexplained share filing followed by a TechCrunch piece two weeks later is a common pattern.
  • Accounts filings. Particularly the first time a company moves out of micro-entity territory into small-company band, or crosses from small to medium. Band transitions are procurement-event catalysts.
  • Striking-off, liquidation, administration notices. Negative signals. Good to track so you can suppress those companies from outreach.

Learning to read these over time gives you context no paid database offers. The information is fresher, more specific, and free.

Building a Companies House watchlist

A minimum-viable watchlist for a small UK B2B team looks like this:

  1. Identify 300 to 500 companies matching your ICP. Save their Companies House numbers.
  2. Subscribe to each via the follow endpoint or an RSS bridge. Every new filing is delivered to you.
  3. Set a filter that highlights director changes, PSC changes, share issuances, and band transitions. Everything else is background noise.
  4. Review weekly. Ten minutes is enough; most filings are routine.
  5. Promote the interesting events into your outreach pipeline with a short note explaining why the filing matters.

This turns a free register into an outreach engine for no cost beyond time.

The API

Companies House offers a free REST API at api.company-information.service.gov.uk. Rate limit: 600 requests per 5 minutes per API key. Enough for any small-to-medium lead-gen operation. Register at developer.company-information.service.gov.uk.

Limits

  • Turnover / balance-sheet / employees only filed by small+ companies (micro-entities file abbreviated accounts)
  • Director personal emails are not in filings
  • Web presence (website, socials) not in Companies House — pair with another source

Common mistakes using Companies House data

  • Treating SIC codes as definitive. A single SIC code is often either too broad (62012 covers enormous ground) or slightly off (a fintech may be registered as 64xxx, not 62xxx). Use SIC as a first-pass filter, not a final one.
  • Relying on registered address. Registered office is the legal address, which is frequently a formation agent or a solicitor’s office. The real trading address is elsewhere. Cross-check with a company’s website footer before making regional inferences.
  • Treating dormant filings as buying signals. Dormant companies are legally alive but trading-inactive. Revival is a genuine signal; routine dormant filings are not.
  • Ignoring the confirmation-statement lag. Confirmation statements have a 14-day filing window after the review date. Changes may be weeks old by the time they appear in the filing. Treat “recent” as a relative term.

Frequently asked questions

Is scraping Companies House allowed? The bulk data and API are published for reuse under the Open Government Licence with attribution. You can legally ingest the lot. The limits are the API rate caps and any commercial terms of sub-services you use to enrich the data.

How much of a typical UK B2B ICP is in Companies House? For Ltd and LLP companies, essentially all of it. For sole traders and ordinary partnerships, none. Your coverage depends on your segment. For most UK SaaS, consultancy, and tech targets, Companies House covers 90%+ of the addressable market.

Can we use Companies House data for outreach directly? Yes, subject to UK GDPR (for personal data like director names) and PECR (for marketing delivery). Public-register data is fair to process under legitimate interest with the usual mitigations.

What is the best way to detect band transitions? Compare turnover and balance-sheet figures filing-to-filing. A company crossing from under £632K to over — moving from micro-entity to small — is a reliable “growing” signal. The same applies at the £10.2M and £36M thresholds.

How LeadKing uses it

Companies House is one of seven signal categories in the LeadKing discovery stack. We watch filings daily and combine with hiring, funding, complaints, tech, regulatory, and news signals — then score candidates per your ICP.

See how it works → or join the waitlist →.