# Sources and what we have not verified

> Where the EORI Lookup Guide gets its facts: Commission and national customs pages, each dated, plus what is still unverified.

- Canonical URL: https://eorilookup.com/sources/
- Checked: 2026-10-21

## Pages we read (21 October 2026)

- [European Commission, Economic Operators Registration and Identification number (EORI)](https://taxation-customs.ec.europa.eu/customs/customs-procedures-import-and-export/customs-operations/economic-operators-registration-and-identification-number-eori_en): definition, who needs one, structure, where to apply, validation links.
- [European Commission, EORI National implementation, 28 June 2022](https://taxation-customs.ec.europa.eu/system/files/2022-06/EORI%20National%20implementation.pdf): formats published for some countries. Older document; national rules may have changed.
- [HMRC design pattern, EORI numbers](https://design.tax.service.gov.uk/hmrc-design-patterns/eori-numbers/): accepted formats for GB and XI numbers and EU prefixes.
- [GOV.UK, Check an EORI number](https://www.gov.uk/check-eori-number): what the UK service checks and where non-GB numbers are sent.
- [GOV.UK, Finding and checking an EORI](https://www.gov.uk/guidance/economic-operators-registration-and-identification-eori/finding-and-checking-an-eori): which checker covers GB, XI and EU numbers, how to find your own GB number.
- [European Commission EORI validation service](https://ec.europa.eu/taxation_customs/dds2/eos/eori_validation.jsp): official check of EU and XI numbers.
- [European Commission, EORI guidance document](https://taxation-customs.ec.europa.eu/document/download/bbe4c653-3b6d-4bed-932c-61bb77711384_en?filename=EN_EORI%20Guidance%20document.pdf): who registers where, database fields, duplicates, carnets, invalidation. The text we read is dated 30 August 2023.
- [GOV.UK, place of registration](https://www.gov.uk/guidance/economic-operators-registration-and-identification-eori/place-of-registration), [who should register](https://www.gov.uk/guidance/economic-operators-registration-and-identification-eori/who-should-register-for-an-eori-number) and [EORI for Northern Ireland](https://www.gov.uk/eori/eori-northern-ireland): GB, XI and EU rules. HMRC pages updated 10 September 2025; the Northern Ireland page 7 August 2025.

## Points we could not settle
1. **Country formats beyond those listed.** The Commission document we used does not state a structure for most EU countries. The checker applies only the general rule for them.
2. **Greece's prefix.** The checker accepts both GR and EL as country codes because we have not confirmed which one the official service uses. This is a point to verify.
3. **Date of the national table.** It is from June 2022 and may be outdated.
4. **UK application steps.** Not summarised here; see GOV.UK.
5. **Batch size and invalid results.** The GOV.UK page we read does not say how many numbers can be checked at once or what to do when a check says invalid.
6. **Country formats.** The list mode applies the same general rule as the single checker.
7. **Guidance version.** The Commission lists a version dated 29 May 2024; the text we read is dated 30 August 2023. Newer wording has not been read.
8. **GB and XI length.** HMRC says 14 characters and also 12 or 15 digits after the prefix. We accept both and have not found an official statement that settles it.
9. **EU numbers in the UK service.** HMRC says they are not accepted for Northern Ireland declarations until further notice. Check the live page.

A customs authority page that answers one of these would help; send the link through [Contact](https://eorilookup.com/contact/).

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