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  1. Fonteum
  2. /
  3. Glossary
  4. /
  5. UK Company Number
Fonteum Data GlossaryData Standards

What is a UK company number?

A UK company number is the Companies House registration number for a company or other registered body. It is the stable identifier used to look up the record, filings, status, registered office, and company profile. UK company numbers are commonly eight characters, including jurisdiction prefixes for some entity types.

Full name: Companies House Company Registration Number

Short explanation

A UK company number, often called a company registration number, is assigned by Companies House and used to retrieve a company profile in the public register. It stays with the registered body even when names or addresses change. In data work, the company number is the source key for Companies House records, while names, registered offices, status, and filings are attributes that can change over time.

Related platform: Entity graph - resolved organization records

Last updated: 2026-07-11Reviewed by: Fonteum data standards desk — Source-provenance editorial review. Definitions checked against primary federal sources.

How it’s used

  • Companies House lookup: the company number is the direct key for public company profiles, filings, registered office details, and status.
  • Bulk company data: Companies House's free company data product uses CompanyNumber as the stable record identifier.
  • Fonteum uses company number as the UK register key and stores changing names, statuses, offices, and filings as dated source facts.

Frequently asked questions

Where do you look up a UK company number?
Use the Companies House register to look up a company by name, number, or officer name.
Does a UK company number change when the company changes name?
No. The company number is the stable Companies House identifier for the registered body.
Is a UK company number the same as a VAT number?
No. The company number identifies the Companies House record. VAT numbers are separate tax identifiers.

Related terms

  • LEI
  • NZBN
  • SIREN
  • SIRET
  • ABN
  • ACN
  • Entity Resolution
  • Provenance

Explore in Fonteum

How Fonteum sources, resolves, and publishes data tied to this term.

  • PlatformEntity graph - resolved organization records
  • PlatformProvider and organization data API
  • PlatformSource provenance model

Authoritative sources

  • Companies House: search the register↗
  • Companies House: free company data product↗
← All glossary terms

What’s on file, by the numbers

Platform snapshot · 2026-07-15

13.4Mproviders & companiesProviders, organizations, owners, and facilities on file
26.2Msource-linked factsSource-linked field facts in the dated platform snapshot
—sources liveCrosswalk-resolved sources with a proved content transition in the preceding 45 days
111sources integratedActive registry rows; integration does not establish a load
13state Medicaid jurisdictionsDistinct states represented in the state-exclusions serving table

Built on the authoritative federal record

The primary sources, named on every page.

These are the federal agencies whose public datasets Fonteum ingests and attributes — the issuing authorities, not customers or partners. Every figure on the site links back to one of them.

  • CMS
  • HHS-OIG
  • HRSA
  • FDA
  • NLM
  • NUCC
  • Census
  • BLS
  • BEA

See the full source registry, with license and refresh cadence for each →

Reproducible by design

Published figures name their source and date.

Source and date

Published research identifies its government file and observation date. Source-file SHA-256 coverage is disclosed separately; facts do not currently link deterministically to signatures.

Reproducible SQL

Each study ships the exact query behind its figures, run against the same dated copy of the federal file we used. Re-run it yourself.

Daily observations

The platform records table row counts daily. Those observations detect local drift; they do not imply that an upstream publisher released or Fonteum ingested new data that day.

Named medical review

Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

Read the full provenance and attestation methodology →

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Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

© 2026 Fonteum LLC. All rights reserved.

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A public-records graph that exposes source and observation metadata where supplied.

Fonteum's provenance ledger contained 26.2M source-linked facts on July 12, 2026. All but 14 carried a source-file SHA-256; 0 linked deterministically to a signature. Inspect a supplied snapshot id at fonteum.com/verify · source-mark coverage and limitations.
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