Company registration number (Company number)
An agreeing value settles the pair on its own, in the stage that compares identifiers and calls no model.
Unique within: One register, and only that register. Not one country: 220 of those 232 jurisdictions run more than one register, so a number plus a country code names a number rather than an organisation.
What your Company number column does in Entity Bind
A company number settles a pair on its own once both sides name the same issuing register, in the second rule of the stage that compares identifier values. Send it as `registration_number`, ideally with `jurisdiction`. It is supplied by Companies House, GLEIF and SIRENE, and carried in the crosswalk qualified by the authority that issued it. The GLEIF registration-authority list is loaded here as reference data so the qualifier can be checked locally, and no customer row is ever sent out to check one.
Your own column will carry gaps and typos the specimen does not, and a few hundred rows will show how much of your file it still settles.
Start freeOn this page
Issuer, shape and a specimen
Every row below is checkable in another tab: the body that assigns the identifier, the exact shape including any check digits, and a specimen value. Where we hold a value we have verified against the issuing body, the specimen is that value; where we do not, it is a shape, labelled as one.
- Issued by
- The register of incorporation — Companies House in the United Kingdom, and one of roughly 1,071 registers worldwide that GLEIF's registration-authority list enumerates across 232 jurisdictions.
- Unique within
- One register, and only that register. Not one country: 220 of those 232 jurisdictions run more than one register, so a number plus a country code names a number rather than an organisation.
- Format
- Register-specific, and the UK case is the one worth stating exactly, because it is the one most often got wrong. Companies House prints exactly eight characters, always — counted from the full Free Company Data snapshot of 2026-08-01, whose 5,695,465 live companies have a company-number length histogram of {8: 5,695,465} with no exceptions. Four families make up those eight characters: eight digits for an ordinary England and Wales company, which is about 89.8% of the register; two letters and six digits for the prefixed families (SC, NI, OC, LP, FC, OE, CE and thirty more); R0 and six digits for Northern Irish companies from before partition; SL, five digits and a final digit or the letter A for a handful of Scottish limited partnerships; and IP, SP or RS with an alphanumeric tail for registered societies, the only GB number space with alphabetic suffixes.
- What one value identifies
- One registration in one register. That is not quite the same as one company: a company that re-registers in another jurisdiction gets a second number in a second register, and a number that has been struck off still names the registration that existed.
- Specimen
- 00617987 — HSBC Holdings plc at Companies House, with the two leading zeros the register prints. Open it on the register and check it against this page.
What goes wrong with Company number
The failure modes that decide whether this column is worth sending, and what each one costs you once it turns up in a live file. Worth reading before you plan an integration around the column.
- 01
Decisive only when both sides name the same issuing authority. A number whose authority is bare, or is only a country code, retrieves candidates and decides nothing, because the authority label GB is not a register — Companies House is one of several bodies issuing GB numbers, and `regno:GB:209603` is a number two unrelated organisations hold honestly. Charity Commission for England and Wales 209603 is the Royal National Lifeboat Institution; Companies House 00209603 is Grange View Investments Limited.
- 02
That collision space is large and has been counted. Measured against the Charity Commission's full register extract of 2026-08-28 and the Companies House product of 2026-08-01, 20,050 company numbers strip to a value that is a real England and Wales charity number. OSCR, the Scottish charity regulator, issues SC plus six digits — character for character what Companies House issues to a Scottish company — and SC003487 is Howwood Parish Church of Scotland at one register and Celtic PLC at the other.
- 03
What rescues the shortcut is the filed shape rather than a country flag. A GB number that could only have come from one register decides; one that could have come from more than one asks for a single corroborating fact first — an agreeing name above a 0.50 similarity floor, or an agreeing domain, phone, postcode, incorporation date or VAT number — and abstains if it gets none. A bare numeric GB number is self-naming only at its full eight digits, and that has a practical consequence for your export: send the zero-padded column if you have it, because a file that dropped the leading zeros gets abstentions where a padded one gets merges.
- 04
Two numbers that differ only where a letter faces the digit it is commonly scanned as — O against 0, I against 1 — return an abstention rather than a non-match. Claiming they are two different registrations would be a stronger statement than the evidence supports: one damaged transcription is far more likely than two companies.
Internal fixtures only. The historical 2026-08-29 per-tier recording covers 317 GB companies with identifier-rich arrivals seeding the catalogue first; the context tier includes country and registered-town prose. Its legacy replay has no full-prompt-verified calls and cannot certify current calibration. The September 5 CI reports cover 1,176 labelled pairs and 705 records over 250 companies using offline stubs. These are not independent customer holdouts or live production validation; the 99% minimum-input product target remains unmet. Scope is company and organisation identity only — not people, vessels, bank-account ownership, sanctions or emissions. Results may not be used for eligibility decisions about individuals, including employment, credit and tenancy.
If one of those is already in your file, a sample turns it into a number of rows instead of a suspicion.
Start freeThe other identifiers on a company record
4 of the 8 settle a pair on their own; the other 4 narrow the field and hand the decision on. If your file carries more than one of them, the question worth settling is which one is doing the work.
LEI
Decides a matchLegal Entity Identifier
CIK
Does not decideCentral Index Key
Ticker
Does not decideExchange ticker symbol
SIREN / SIRET
Decides a matchSIREN and SIRET
D-U-N-S
Decides a matchData Universal Numbering System number
VAT number
Does not decideVAT registration number
EUID
Does not decideEuropean Unique Identifier
Or try your own rows: create your Free workspace and upload a company CSV to inspect the decisions and receipts. Where a further column would settle an unresolved row, it names that column; contact us for an assisted review.
Start freeWhere Company number shows up elsewhere
The rest of the answer, on the shelves that hold it. Each card names its own — a register, a definition, a guide or a comparison — and opens on the page that carries it at length.
- JurisdictionUnited KingdomCompanies House under the Open Government Licence v3.0, storable and resellable. The register every published tier rate on this site was recorded on.
- Also listed byUnited StatesThere is no national company register in the United States. Coverage is Colorado, as public-domain bulk data, plus SEC EDGAR. Delaware publishes nothing.
- Also listed byFranceSIRENE under Licence Ouverte 2.0, storable and resellable, and the only register that links a site to the legal entity running it. Bare names meet a ceiling.
- Also listed byNorwayBrønnøysund's Enhetsregisteret is the only register here publishing a telephone number, one of two publishing a website, with three insolvency flags.
- DefinitionCompany numberA company number is the identifier a register assigns to a company at incorporation, and it is unique only within the register that issued it — never within a country and never globally.
- DefinitionDeterministic matchingDeterministic matching decides a pair by an explicit rule — usually agreement on a strong identifier — and produces the same verdict every time with no score in between.
- DefinitionAbstentionAn abstention is a first-class 'we do not know' returned instead of a match: the record comes back unresolved, with a ranked shortlist, a typed reason and the column that would have decided it.
- GuideCompany identifiers explainedCompany number, LEI, CIK, ticker, SIREN and SIRET, DUNS, VAT, EUID and ISIN. What each identifies, who issues it, what it does not guarantee, and which ones actually decide a match.
- GuideKYB data requirementsWhat a know-your-business onboarding flow actually needs, field by field, and which step is identity resolution. Explicitly not a screening, scoring or eligibility tool.
- ComparisonThe Companies House APIFree, authoritative, and the right answer for a lot of UK teams. It is one of our sources too.
- ComparisonOpenCorporatesAn excellent register mirror. A register mirror is not a decision.
Sources
The bodies and records this page quotes about Company number, each with the caveat that travels with it.
- Companies House register search
The register the United Kingdom figures were measured on. A name-uniqueness share is a property of the register, not of any resolver.
- Open Government Licence v3.0
The instrument Companies House publishes under. It is what makes those facts storable and resellable rather than return-only.
- HSBC Holdings plc, 00617987, at Companies House
The specimen on the company number page, on the register that issued it. Checked on 2026-09-25.
- GLEIF Registration Authorities List
The register of registers. The 1,071 registers across 232 jurisdictions quoted on this site were read from GLEIF's registration-authorities API when the list was loaded, and the API still reported 1,071 on 2026-09-25; the list is versioned, so those counts move with it.
- Charity Commission for England and Wales
The regulator whose register extract the charity-number collision was counted against. Scotland's OSCR is a separate regulator under a different instrument.
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Questions about Company number
How do I prepare a UK company number for matching?
Preserve the full number as text, including leading zeros and any prefix. For a fictional Tutorial Willow Ltd row, compare the supplied number and jurisdiction with the Companies House record before accepting a spelling variant. A number from another register is a different identifier space. Retain the issuing authority in your source data and verify that the number belongs to this row.
Why do you need the jurisdiction as well as the company number?
Because a company number is only an identifier inside the register that issued it. GLEIF lists 1,071 registers across 232 jurisdictions and 220 of those jurisdictions run more than one, so a number on its own — and, in several countries, a number plus a country code — names a string rather than an organisation. We hold the GB registers and the number shapes each one issues as data, and an identifier decides a pair only where exactly one register could have issued the number as filed. Where more than one could have, the pair has to corroborate on something else before the number is allowed to be decisive, and where it cannot corroborate it comes back as an abstention with the shortlist.
My export dropped the leading zeros from our company numbers. Does that matter?
Yes, and it matters in a specific direction. Companies House numbers are always eight characters, so 209603 in your file is 00209603 at the register — but 209603 is also a real Charity Commission number, and 20,050 company numbers in the 2026-08-01 snapshot strip to a value that is a live England and Wales charity number. An unpadded number is therefore ambiguous rather than merely untidy, and the engine handles that by refusing the automatic answer: the pair abstains unless one other fact agrees across it. You get abstentions where a padded file would have got merges. The fix is to send the padded column, and the unresolved rows will name that column as the thing to repair.