What is a company number?

Every company registered with Companies House has an 8-character company number. Pure numeric numbers (e.g. 00445790) are England & Wales or Scotland. Special prefixes denote special types: SC (Scotland alternative format), NI (Northern Ireland), OC (LLP - Limited Liability Partnership), LP (Limited Partnership), FC (UK establishment of overseas company), OE (Overseas Entity), CE (CIO - Charitable Incorporated Organisation), and others.

What is a PSC (Person with Significant Control)?

A PSC is anyone who owns more than 25% of a UK company's shares or voting rights, or otherwise exercises significant control. Since 2016 every UK company must publish its PSCs in the Companies House register. PSCs can be individuals (natural persons), corporate entities, or other legal persons. Prometiam serves the full PSC register — 22.0M records covering all UK companies.

Standard Industrial Classification of Economic Activities — the 5-digit code Companies House uses to classify what a UK company does. UK SIC 2007 (e.g. 62020 = 'Information technology consultancy activities'). Companies can declare up to 4 SIC codes. SIC is the UK equivalent of CNAE in Spain or NAF in France.

Is Companies House data free?

Yes. Companies House publishes the BasicCompanyData product as a monthly free bulk download (~5.7M companies, ~500MB compressed CSV across 7 slices), the full PSC register as a daily snapshot (~7M records, ~2GB JSON), and individual company profiles via a free-tier REST API (600 requests per 5 minutes per key). Filings PDFs are also free.

Why does the bulk product only have ~5.7M companies when CH has issued 17M+ numbers?

The BasicCompanyData bulk product only contains companies that are currently active or recently dissolved. Companies dissolved more than ~6-12 months ago are dropped from the bulk dump but remain queryable individually via the REST API at /company/{number}. Prometiam includes those older dissolved companies, so a counterparty that closed years ago still resolves.

How do I query UK companies programmatically?

Use the Prometiam company data API. GET /companies/search?country=GB&company_number=00445790 returns TESCO PLC. GET /companies/search?country=GB&name=tesco does a fuzzy-match search. Free tier: 1,000 requests/month with no credit card required; Starter (€9.99/month) raises that to 10,000.

What is Companies House?

Companies House is the executive agency of the UK government that registers and dissolves limited companies. It operates under the Companies Act 2006 as part of the Department for Business and Trade, and is the public record of record for every UK limited company, LLP, Limited Partnership, Charitable Incorporated Organisation, and Community Interest Company.

The data it publishes

Companies House releases data in three forms: the BasicCompanyData monthly bulk CSV (~5.7M active and recently-dissolved companies, ~500MB across 7 slices); the PSC register daily JSON snapshot (~7M Persons with Significant Control); and a free-tier REST API (600 requests per 5 minutes) covering company profiles, officers, filing history, and mortgage charges.

Reading a company number

Every registration has an 8-character company_number whose prefix encodes legal form: plain 8-digit numbers are England & Wales / Scotland, SC is Scotland alternative, NI Northern Ireland, OC an LLP, LP a Limited Partnership, FC an overseas company's UK establishment, OE an Overseas Entity, CE a CIO. Always preserve the leading zeros. A SIC code (UK SIC 2007) classifies activity.

Companies House vs The Gazette

Insolvency events are not in Companies House — they appear in The London, Edinburgh, and Belfast Gazette. A full UK risk picture needs both feeds.

How Prometiam serves it

Prometiam serves UK companies, officers, PSC beneficial owners, corporate events and Gazette insolvency notices through one REST API — currently 7.71M UK companies, 22.0M PSCs, 5.7M officers and 33.46M appointments, queryable behind ?country=GB alongside Spain, France, Ireland, Poland and Norway. Beneficial ownership covers UK PSC only.

Reading a UK company number

Prefix	Meaning	Example	UK count
`0X-9X` (8 digits)	England & Wales / Scotland numeric	`00445790` (Tesco PLC)	5.1M
`SC`	Scotland (alternative format)	`SC084330`	275K
`NI`	Northern Ireland	`NI012345`	89K
`OC`	LLP (Limited Liability Partnership)	`OC301337`	48K
`LP`	Limited Partnership	`LP001234`	22K
`FC`	UK establishment of overseas company	`FC012345`	14K
`OE`	Overseas Entity (post-2022 register)	`OE001234`	30K
`CE`	Charitable Incorporated Organisation	`CE012345`	39K
`SL / IP / CS / RC / RS / SO`	Various Scottish Limited Partnership / Provident Society / etc.	—	~62K

Frequently asked questions

What is Companies House?: Companies House is the United Kingdom's executive agency that registers and dissolves limited companies, files company information, and makes that data available to the public. It is part of the Department for Business and Trade (DBT) and operates under the Companies Act 2006.
What is a company number?: Every company registered with Companies House has an 8-character company number. Pure numeric numbers (e.g. 00445790) are England & Wales or Scotland. Special prefixes denote special types: SC (Scotland alternative format), NI (Northern Ireland), OC (LLP - Limited Liability Partnership), LP (Limited Partnership), FC (UK establishment of overseas company), OE (Overseas Entity), CE (CIO - Charitable Incorporated Organisation), and others.
What is a PSC (Person with Significant Control)?: A PSC is anyone who owns more than 25% of a UK company's shares or voting rights, or otherwise exercises significant control. Since 2016 every UK company must publish its PSCs in the Companies House register. PSCs can be individuals (natural persons), corporate entities, or other legal persons. Prometiam serves the full PSC register — 22.0M records covering all UK companies.
What is a SIC code?: Standard Industrial Classification of Economic Activities — the 5-digit code Companies House uses to classify what a UK company does. UK SIC 2007 (e.g. 62020 = 'Information technology consultancy activities'). Companies can declare up to 4 SIC codes. SIC is the UK equivalent of CNAE in Spain or NAF in France.
Is Companies House data free?: Yes. Companies House publishes the BasicCompanyData product as a monthly free bulk download (~5.7M companies, ~500MB compressed CSV across 7 slices), the full PSC register as a daily snapshot (~7M records, ~2GB JSON), and individual company profiles via a free-tier REST API (600 requests per 5 minutes per key). Filings PDFs are also free.
Why does the bulk product only have ~5.7M companies when CH has issued 17M+ numbers?: The BasicCompanyData bulk product only contains companies that are currently active or recently dissolved. Companies dissolved more than ~6-12 months ago are dropped from the bulk dump but remain queryable individually via the REST API at /company/{number}. Prometiam includes those older dissolved companies, so a counterparty that closed years ago still resolves.
How do I query UK companies programmatically?: Use the Prometiam company data API. GET /companies/search?country=GB&company_number=00445790 returns TESCO PLC. GET /companies/search?country=GB&name=tesco does a fuzzy-match search. Free tier: 1,000 requests/month with no credit card required; Starter (€9.99/month) raises that to 10,000.