EORI numbers: what they are, how they look, and where to check them

What this tool does, and what it does not

• It checks the format. It tests the country code and the length against the rules in the official guidance, and tells you which official service to use next.
• It does not check registration. Only the official services can tell you whether a number is registered. Use the EU validation service for EU numbers and for numbers starting with XI, or the UK service for numbers starting with GB.
• It sends nothing. The check runs in your browser. Nothing you type leaves your device.

Briefly

• An EORI number identifies an economic operator in customs. It is a two-letter country code followed by a number that is unique in that country. The number part can be up to 15 letters or digits (European Commission).
• A person can hold only one valid EORI number at a time.
• You get it from one customs authority: the national authority of the country where you are established (European Commission).
• UK numbers (GB) and Northern Ireland numbers (XI) are the prefix plus 12 or 15 digits (HMRC's pattern; its text also says 14 characters, see sources) (HMRC pattern).

The app above

The first tab checks one number or a whole list and tells you which official service confirms each. The second asks four questions to tell you whether you need an EORI. The third tells you where to apply, since only one customs authority can assign your number.