UK identifiers — EORI, VAT, Companies House

To invoice or clear customs in the UK, three identifiers matter. The EORI number (Economic Operators Registration and Identification) identifies an operator at customs — now indispensable for GB-EU trade since Brexit. The VAT number (GB prefix) identifies the taxable person. The Company Registration Number from Companies House identifies the company. These three numbers, issued by separate authorities, must never be confused.

History — EORI and the 2021 customs break

The UK companies register dates from the 19th century: since the Joint Stock Companies Act 1844, each company receives a unique Company Registration Number, now managed by Companies House. VAT arrived in 1973 with EEC accession, and HMRC assigns VAT numbers.

The EORI system was introduced in 2009 EU-wide to identify operators at customs. While the UK was in the single market, the EORI was barely used for intra-EU trade. Brexit changed everything: since 1 January 2021, GB-EU trade is import/export, and a GB EORI becomes indispensable. The Northern Ireland Protocol adds an XI EORI for Northern Ireland, which keeps a special customs status.

1844       | The Joint Stock Companies Act creates the companies register
           | — ancestor of Companies House, which since then assigns a
           | unique Company Registration Number to each company.
           |
1973       | VAT introduced; HMRC (then Customs & Excise) assigns a VAT
           | number to registered taxable persons.
           |
2009       | The EORI system replaces TURN (Trader's Unique Reference
           | Number) across the EU to identify economic operators at
           | customs. UK EORI prefixed GB.
           |
2021-01-01 | Brexit takes effect on customs: GB-EU trade becomes
           | import/export again. A GB EORI becomes indispensable to clear
           | goods, where it was needless within the single market.
           |
2021       | Separate EORIs introduced for Northern Ireland (prefix XI)
           | under the Northern Ireland Protocol, to manage NI's special
           | status.
           |
2023-2026  | Stabilisation: GB EORI for Great Britain, XI EORI for
           | Northern Ireland, integration into CDS (Customs Declaration
           | Service). Companies House modernises its public API.

Governance — HMRC + Companies House

HMRC issues and manages the EORI and the VAT number. The EORI is obtained online on gov.uk, usually within a few days; it is often derived from the VAT number (9-digit VAT + 000). Companies House, an executive agency of the Department for Business and Trade, maintains the public companies register and assigns the Company Registration Number at incorporation.

Companies House publishes a public API to verify a company's existence, address and officers — useful to clean up invoicing data. HMRC provides a UK VAT number checking service (and, for the EU, the VIES service on the European counterparty side).

Technical schema — identifier composition

Each identifier has a precise format. Confusing them on an invoice or a CDS declaration causes rejections:

EORI number (GB)           GB123456789000
  GB + 12 digits (often VAT 9 digits + 000)
  Northern Ireland variant   XI123456789000

VAT number                 GB 123 4567 89
  GB + 9 digits (standard format, sometimes + 3 branch
  digits for groups). On invoice: "VAT Reg No".

Company Registration No.   12345678
  8 characters from Companies House (digits, or 2 letters +
  6 digits: SC in Scotland / NI in Northern Ireland). On a
  Ltd invoice: mandatory with the registered office address.

PEPPOL addressing          ICD 0088 (GS1 GLN) or 9932 (GB VAT)
  Routing identifier on the PEPPOL 4-corner network.

• GB EORI — GB + 12 digits; for a VAT-registered trader, typically the VAT (9 digits) suffixed with 000.
• XI EORI — XI prefix for Northern Ireland-related flows.
• VAT — GB + 9 digits; a check algorithm (modulo 97) validates the number.
• Company number — 8 characters; SC (Scotland), NI (Northern Ireland), otherwise numeric for England/Wales.
• PEPPOL ICD — 0088 (GS1 GLN) or 9932 (GB VAT) for network addressing.

EORI vs VAT vs Companies House

Adoption — use on invoices and at customs

• On a Ltd invoice — the Company number and registered office address are mandatory (Companies Act 2006), and the VAT Reg No is mandatory if the business is VAT-registered.
• On a CDS customs declaration — the importer's and exporter's EORI is required; without a valid EORI, no clearance.
• In EDI / PEPPOL — addressing relies on the GLN (ICD 0088) or the GB VAT (ICD 9932) depending on the counterparty's profile.
• Automated verification — the Companies House API and the VAT checking service help validate partner data before issuance.

Common pitfalls

• Using the VAT as an EORI. The VAT alone is not enough at customs: the full EORI (GB + 12 digits) is required, even if it derives from the VAT.
• Forgetting the XI EORI. Northern Ireland-related flows often require a distinct XI-prefixed EORI rather than the GB one.
• Confusing Company number and VAT. The Company number (Companies House) is not a tax number; it validates no VAT operation.
• Incorrect VAT format. A mis-keyed 9-digit GB VAT fails the modulo-97 check and the HMRC verification service.
• Ignored Scottish/NI prefix. A Scottish company number starts with SC; truncating it to numeric breaks the Companies House lookup.

Cross-links

• United Kingdom hub — full view
• Post-Brexit customs — CDS
• UK VAT regimes
• Making Tax Digital for VAT
• gov.uk — Get an EORI number
• Companies House
• gov.uk — Check a UK VAT number