The bottom line

Companies House is the UK's public registry of corporations. Every UK-incorporated company — public, private, dormant — must file at minimum: an annual confirmation statement (CS01), annual accounts, and a register of People with Significant Control (PSC). Most of this is free to access, machine-readable, and updated within days. Compared to the US, UK transparency is much higher for private companies (annual accounts are mandatory and public for nearly all UK companies, vs roughly zero for US private companies). Understanding what each filing reveals is the difference between a 5-minute lookup and a paid corporate-investigations engagement.

What Companies House is

Companies House is the UK's register, run by the Department for Business and Trade. Every UK-incorporated entity must file with it, including:

  • Public Limited Companies (PLCs) — listed and unlisted.
  • Private Limited Companies (Ltd) — the vast majority of UK businesses.
  • Limited Liability Partnerships (LLPs).
  • Companies Limited by Guarantee (charities and not-for-profits).
  • Community Interest Companies (CICs).
  • Various unusual forms: oversea companies, European companies (under transitional rules), unregistered companies.

Each company has a permanent Companies House number (8 digits, sometimes prefixed by SC for Scotland or NI for Northern Ireland). The number is the canonical identifier across all filings.

You search at find-and-update.company-information.service.gov.uk for free, including downloads of every filed document as PDF.

What every UK company must file

The annual core filings:

Confirmation Statement (CS01) — formerly the “annual return.” A snapshot of the company's key information: registered office, directors, secretary (if any), nature of business (SIC codes), share capital structure, shareholders (for some companies), trading status. Filed every 12 months, must be confirmed within 14 days of the “made up to” date. £13 fee online. Always public.

Annual Accounts — the financial statements. Filing format depends on company size:

  • Small companies (turnover < £10.2M, balance sheet < £5.1M, employees < 50) can file abbreviated accounts: just the balance sheet + notes.
  • Medium-sized companies must file the full balance sheet, income statement, and notes.
  • Large companies must file full audited accounts, directors' report, strategic report.
  • Micro-entities (turnover < £632k, balance sheet < £316k, employees < 10) can file very minimal balance-sheet-only accounts.

This is a major UK-vs-US transparency advantage: US private companies file ~nothing publicly; UK private companies file at least a balance sheet annually.

Register of People with Significant Control (PSC) — disclosure of anyone owning more than 25% of shares, more than 25% of voting rights, or who has the right to appoint a majority of directors. The PSC register is deeply informative — it's where ultimate beneficial ownership of UK companies is publicly recorded. The 2023 Economic Crime and Corporate Transparency Act tightened verification requirements; companies and PSCs face larger penalties for misreporting.

Officer changes — director appointments, resignations, address changes. Filed within 14 days of the change.

Other event-driven filings — share allotments (SH01), changes to share capital, charges/mortgages (MR01), capital reduction, name changes, registered office changes, voluntary strike-off applications.

What the PSC register actually reveals

PSC is the closest UK equivalent to true beneficial-ownership disclosure. For each PSC, the register shows:

  • Name (full name for individuals; full legal name for entities).
  • Service address (often the company's, not the residential).
  • Country of usual residence (for individuals).
  • Date of birth (month and year only — day is suppressed).
  • Nature of control — typically a category code like “ownership-of-shares-25-to-50-percent” or “significant-influence-or-control.”
  • Date the person became a PSC.

For corporate PSCs, the registered office and registry number of the holding entity. Following the chain through multiple PSCs sometimes lets you identify the ultimate beneficial owner (UBO).

This disclosure exists nowhere comparable in the US. It is one of the most useful single sources for UK corporate due diligence.

Worked example: tracing ownership via PSC

You want to understand who really owns “Acme Holdings (UK) Ltd.”

Step 1: Search Companies House for Acme Holdings (UK) Ltd. Get its company number (e.g., 12345678).

Step 2: Open the PSC register. It shows: PSC = “Acme Group BV,” a Dutch company.

Step 3: Acme Group BV is in the Dutch trade register, not Companies House — but its UK subsidiary's PSC entry shows you exactly who owns the UK piece.

Step 4: If Acme Holdings (UK) Ltd has another UK subsidiary, search that subsidiary's PSC and confirm Acme Holdings (UK) Ltd is its PSC.

Step 5: For multi-jurisdiction structures, Companies House gets you the UK piece. The non-UK pieces require their own registries (Dutch KVK, Luxembourg RCSL, Cayman Islands General Registry, etc.).

Real-world investigations stitch together multiple jurisdictions. UK is unusually transparent compared to many; some others (US states, BVI, Cayman) are more opaque.

What an annual accounts filing reveals

For a private UK company filing full accounts:

  • Balance sheet — assets, liabilities, equity at the year-end date.
  • Income statement — revenue, gross profit, operating profit, profit/loss for year. (For small companies with abbreviated accounts, only the balance sheet is filed; income detail may be opt-out.)
  • Cash flow statement (medium and large only).
  • Notes — accounting policies, related-party transactions, employee numbers and average wage cost (a reliable cross-check on size and concentration), directors' remuneration disclosure.
  • Directors' report — narrative on the year.
  • Strategic report (medium and large) — broader narrative including KPIs.
  • Auditor's report (medium / large or required) — going concern, material weakness, qualifications.

Even a micro-entity balance sheet tells you: total assets, debt level, share capital, and (often by inference) profitability via retained-earnings change year-over-year.

Companies House vs UK CIC / Charities Commission

Charities and CICs file with overlapping registries:

  • Charities Commission for England and Wales — separate registry; charity accounts published.
  • OSCR — Scottish charity regulator.
  • Charity Commission for Northern Ireland.

CICs file with Companies House for corporate matters and with the CIC Regulator for the asset-lock and community-benefit declarations.

For non-trading entities, also check OSCR / CCEW / CCNI as appropriate.

Common mistakes

1. Treating Companies House as a US-EDGAR equivalent. Listed-company filings (LSE / AIM-listed PLCs) are governed by the FCA — Companies House has the corporate-law filings; the FCA / RNS holds the markets-disclosure stream. For listed companies, both registries matter.

2. Trusting the PSC register completely. Verification has improved (2023 ECCTA), but historical PSC entries can be incomplete, lag, or use nominee structures. Cross-check against operational data when due-diligence stakes are high.

3. Reading micro-entity accounts as full disclosure. They aren't — micro-entity rules permit very minimal balance sheet only. Often there's no income detail at all.

4. Missing the registered office. Many UK companies use a service-provider address (formation-agent box). The registered office isn't a fact about where the business operates; it's a fact about where the company can be served.

5. Forgetting filing-deadline tolerance. Late accounts trigger automatic financial penalties (£150 → £1,500 depending on lateness and company type). Persistently late filings can lead to strike-off; the company is dissolved and assets escheat. This is itself a useful signal.

How to query Companies House programmatically

For automated workflows, Companies House offers a REST API:

  • Free tier with rate-limiting (600 requests per 5 minutes).
  • Endpoints for company profile, officers, PSC, filing history, charges, address.
  • API key required (free signup at developer.company-information.service.gov.uk).
  • All data returned as JSON; raw filings as PDF.

The infoz.com UK company profile pages (when launched) will surface this data structured by company, with PSC chains traced where possible and accounts trends shown over time.

What this guide does NOT cover

  • Listed-company FCA / RNS announcements (separate regulatory stream)
  • Director disqualification register (gov.uk separate)
  • Insolvency Service registers and bankruptcy proceedings
  • HMRC tax filings (largely not public)
  • Trade-mark and patent registries (UK IPO)
  • Land Registry for UK real-estate ownership
  • Beneficial-owner registries in other jurisdictions

For UK due-diligence engagements involving real money — M&A, hiring, vendor onboarding — Companies House is the starting point. Combine with secondary sources (Endole, OpenCorporates) for richer search and historical archives.