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UK Company Identifiers

Understanding the UK company numbering system.

Company Numbers​

Every UK company has a unique 8-character identifier assigned by Companies House.

Format​

  • Length: Always 8 characters
  • Padding: Left-padded with zeros
  • Characters: Numbers and sometimes letters

Examples​

  • 00445790 - Standard format (Tesco PLC)
  • SC123456 - Scottish company
  • NI123456 - Northern Ireland company
  • OC123456 - Limited Liability Partnership

Prefix Meanings​

PrefixTypeJurisdiction
(none)Standard companyEngland & Wales
SCCompanyScotland
NICompanyNorthern Ireland
OCLLPEngland & Wales
SOLLPScotland
NCLLPNorthern Ireland
RRoyal CharterUK

Number Ranges​

Companies are numbered sequentially within ranges:

  • 00000001-09999999: England & Wales companies
  • SC000001-SC999999: Scottish companies
  • NI000001-NI999999: Northern Ireland companies
  • OC300000-OC999999: LLPs

Finding Company Numbers​

Ask Claude:

"Search for companies named Tesco"

Claude will use the search_companies tool and return company numbers like "00445790".

From Companies House​

  1. Visit Companies House
  2. Search by name
  3. Company number shown in results

From Documents​

Look for company number on:

  • Letterheads
  • Invoices
  • Websites (footer)
  • Terms & Conditions

Validation Rules​

Format Requirements​

  • Standard: 8 digits (e.g., "00445790")
  • Scottish: SC + 6 digits (e.g., "SC123456")
  • Northern Ireland: NI + 6 digits (e.g., "NI123456")
  • LLP: OC + 6 digits (e.g., "OC123456")
  • Scottish LLP: SO + 6 digits
  • NI LLP: NC + 6 digits

All prefixes must be uppercase. Numbers must be padded with leading zeros.

Using Identifiers with Claude​

Direct Lookup​

"Get details for company number 00445790"

With Company Name​

"Find information about Tesco PLC"

Claude automatically handles the lookup and uses the correct company number.

Smart Suffix Handling​

"Look up ABC Limited"

Claude strips common suffixes (LIMITED, LTD, PLC, LLP) automatically.

Best Practices​

  1. Always use 8 characters: Pad with leading zeros
  2. Preserve format: Company numbers are strings, not integers
  3. Case sensitive: Prefixes are uppercase
  4. Use full names: Claude handles suffix stripping

Common Issues​

Missing Leading Zeros​

  • Wrong: "445790"
  • Correct: "00445790"

Always use the full 8 characters with leading zeros.

Wrong Prefix Case​

  • Wrong: "sc123456"
  • Correct: "SC123456"

Prefixes must be uppercase.

Charity Number​

  • Registered charities have additional numbers
  • Format varies by jurisdiction
  • Searchable separately through charity registers

Note: VAT numbers and PAYE references are not available through this MCP server.