Companies House Data Explained: What's Available and How to Use It

Companies House is one of the UK's most valuable public data sources, yet most people barely scratch the surface of what it offers. Whether you're a salesperson looking for leads, a researcher analysing market trends, or a business owner checking a potential partner's credibility, understanding what data is available — and how to access it — can give you a significant edge.

What is Companies House?

Companies House is the United Kingdom's official registrar of companies. It's an executive agency sponsored by the Department for Business and Trade, and it has existed in various forms since 1844. Its primary role is to incorporate and dissolve limited companies, examine and store company information, and make that information available to the public.

Every limited company, limited liability partnership (LLP), limited partnership (LP), and certain other business entities registered in England, Wales, Scotland, and Northern Ireland must file information with Companies House. This information is, by law, publicly available.

What data is publicly available?

The breadth of data available through Companies House is substantial. Here's a breakdown of the key data categories:

Company profile data

For every registered company, you can access:

• Company name and any previous names
• Company number — a unique 8-digit identifier
• Registered office address
• Date of incorporation
• Company status (active, dissolved, liquidation, etc.)
• Company type (private limited, PLC, LLP, etc.)
• SIC codes — the Standard Industrial Classification codes that describe the company's business activities
• Accounting reference date

Officer data (directors and secretaries)

For every company, the following officer information is publicly available:

• Full name of each director and secretary
• Date of birth (month and year only — the day is suppressed)
• Nationality
• Occupation
• Usual residential country
• Appointment and resignation dates
• Correspondence address (not necessarily their home address)

It's worth noting that since 2016, Companies House no longer displays the day of birth for directors in public records, and home addresses filed as "service addresses" may be the registered office rather than a personal address.

Persons of significant control (PSC)

Since 2016, companies must declare individuals who hold significant control — typically those with more than 25% of shares or voting rights. The PSC register reveals:

• The individual's name and date of birth
• Their nationality and country of residence
• The nature and extent of their control

Filing history

Every document filed with Companies House becomes part of the public record. This includes:

• Annual accounts (including balance sheets, profit and loss statements for larger companies)
• Confirmation statements (annual returns)
• Articles of association and memoranda
• Charges (mortgages and security interests)
• Resolutions and change-of-name certificates

The level of financial detail varies by company size. Micro-entities and small companies can file abbreviated or filleted accounts, which contain far less detail than the full accounts required of medium and large companies.

How to access Companies House data

The Companies House website

The simplest way to look up individual companies is through the Companies House web service. You can search by company name, number, or officer name. It's free and requires no registration. However, it's designed for looking up one company at a time — not for bulk research or lead generation.

The Companies House API

For developers and businesses that need to query data programmatically, Companies House offers a free REST API. The API provides access to:

The API is rate-limited to 600 requests per five minutes. While this is adequate for ad-hoc queries, it becomes a bottleneck when you're trying to pull data on thousands of companies. There's also no built-in endpoint for "show me all companies incorporated today" — you need to use the streaming API or bulk data products to achieve that.

Bulk data products

Companies House also provides free bulk data downloads, including the entire company register as a CSV file and monthly snapshots of officer appointments. These files are large (several gigabytes), require significant processing, and need to be updated regularly to remain current.

Understanding SIC codes

One of the most valuable data points for lead generation is the SIC code (Standard Industrial Classification). Every company must declare at least one SIC code when it incorporates, describing its primary business activity.

SIC codes follow a hierarchical structure. For example:

This classification system is powerful for lead generation because it lets you target specific industries. If you sell insurance to construction companies, you can filter for SIC codes starting with 41-43. If you provide accounting services to IT firms, you'd filter for codes in division 62-63.

The limitation is that SIC codes are self-declared and sometimes inaccurate. A company might choose a generic code like "74909 — Other professional activities not elsewhere classified" when a more specific one exists. Despite this, SIC codes remain the best publicly available method for classifying UK businesses by industry.

Limitations of Companies House data

While Companies House is an extraordinary resource, it's important to understand its limitations:

• No email addresses or phone numbers. Companies House collects registered office addresses and officer details, but not direct contact information like emails or phone numbers.
• Sole traders and partnerships aren't included. Only limited companies, LLPs, and LPs are required to register. Sole traders and ordinary partnerships don't appear at all.
• Data quality varies. Some companies file late, some provide minimal information, and some SIC codes are poorly chosen.
• No trading status indicator. A company can be "active" on the register but dormant or not yet trading. There's no reliable way to determine from Companies House data alone whether a company is genuinely operational.
• Financial data is limited for small companies. The vast majority of UK companies qualify as small or micro-entities and file abbreviated accounts with minimal financial disclosure.

How businesses use Companies House data

Despite these limitations, Companies House data is used extensively across the UK business ecosystem:

Lead generation: B2B service providers use new incorporation data to identify and reach potential clients at the earliest possible stage. Accountants, insurance brokers, web agencies, and business service providers all benefit from early access to new company data.

Due diligence: Before entering into a business relationship, companies routinely check their counterpart's Companies House record to verify they're a legitimate, active entity and to review their filing history and financial position.

Market research: Analysts and researchers use Companies House data to track incorporation trends, analyse sector growth, and understand regional business formation patterns.

Compliance and KYC: Financial institutions use Companies House data as part of their Know Your Customer (KYC) processes, verifying company details and officer identities.

Key takeaways

Companies House holds data on over 5.5 million active UK companies, including registration details, officer information, SIC codes, and filing history. The data is freely available via a web service, REST API, and bulk downloads. SIC codes are the primary method for classifying companies by industry. Key limitations include the absence of contact details, no coverage of sole traders, and variable data quality. For lead generation, services like NewCo Data process and enrich Companies House data into actionable, sector-filtered lead reports — saving hours of manual work.