Company number

A company number is the identifier a register gives a company when it incorporates. Companies House issues eight-character numbers, optionally with a letter prefix that encodes the jurisdiction or company type. Other registers use entirely different shapes. The number is authoritative for the register that assigned it and means nothing outside it.

The most common and most expensive mistake in company data is treating 'company number plus country' as a unique key. It is not: many jurisdictions run more than one register, German numbers are qualified by the court that holds them, and several countries operate parallel number spaces for tax, statistics and incorporation. A record whose number is stored without its issuing authority has lost information that cannot be recovered by inspection, because the shapes overlap.

The second common mistake is normalising the number as if it were an integer. Stripping leading zeros or a letter prefix creates collisions with other schemes, and a six-digit remainder can look like a completely different kind of reference.

Entity Bind stores registration numbers scoped to their issuing authority, checks register shape rather than string equality, and treats conflicting authority-scoped numbers as a decisive non-match rather than as a weak negative signal. Name uniqueness in the register is measured before any claim is made about name matching: on Companies House's 5,464,811 live companies, 99.53% of names are unique.