The Government have confirmed that businesses moving goods to or from Northern Ireland (NI) will need a special EORI number with a ‘XI’ country prefix.
The Government have stated:
If you move goods to or from Northern Ireland
From 1 January 2021 you’ll need an EORI number that starts with XI to:
move goods between Northern Ireland and non-EU countries
make a declaration in Northern Ireland
get a customs decision in Northern Ireland
To get an EORI number that starts with XI, you must already have an EORI number that starts with GB. If you do not have one, apply for an EORI number that starts with GB as soon as possible.
If you already have an EORI number that starts with GB and HMRC thinks you need one that starts with XI, they’ll automatically send you one in mid-December 2020.
A safety and security statement, sometimes referred to as an "entry summary declaration" or "ENS," will be required for any items imported into the United Kingdom from the European Union as of January 31, 2025.
UK exporters are advised by HMRC to enrol in the Customs Declaration Service (CDS), which will be necessary for export declarations beginning on March 31, 2024.