Do I need an EORI number? In short, the answer is most probably yes.
You need an EORI number to move goods into or out of the EU (including the UK). If you do not get one, you may have increased costs and delays. Gov.uk
An EORI number is an Economic Operator Registration and Identification number. It is used for statistics, security and by customs authorities when exchanging information between themselves and government departments and agencies. Without an EORI number, your goods won't be cleared through customs.
If there's a no-deal Brexit, you'll need an EORI number that starts with 'GB' to move goods in or out of the UK.
If you already have an EORI number (VAT registered users can check on the EU EORI number validation website) that starts with 'GB' and is 12 digits long, you can continue to use it. Your VAT registration number will be included if you are VAT registered.
If you want to trade with an EU country, you will also need an EU EORI number. This will start with the country code of the EU country you acquired it from. An EU EORI number can be claimed from the customs authority in the EU country you trade with first.
It is worth noting that you do not need an EORI number if you will only be moving goods between Northern Ireland and Ireland.
Before applying for a UK EORI number, you will need
Applying for an EORI number takes approximately 10 minutes, and will either be available immediately or provided within 5 working days (if more HMRC checks are required). You may have to wait around 48 hours before your EORI number can be used for customs declarations in the CHIEF (Customs Handling of Import and Export Freight) system.
It is worth noting that the HMRC is now auto-enrolling some businesses with UK EORI numbers. However, this only applies to certain businesses, which have already traded goods with the EU in 2018, so it is worth making sure that you have applied.
For more information and to apply, visit the Gov.uk 'Get an EORI number' application website.