Any business that is VAT-registered and currently trades with the EU will have automatically been issued with an EORI number allowing it to trade with customers and suppliers in EU member states following the UK’s withdrawal from the EU. 

However, businesses that are not registered for VAT will need to register for an EORI number that will enable them to be identified by customs authorities.

Some VAT-registered businesses that do not currently trade with the EU, but have intentions to in the future, may not receive an EORI number automatically. They should acquire an EORI number to assist with their trade plans.

On receipt of an EORI number, businesses must determine whether to instruct a customs agent to complete customs declarations on their behalf or to do so themselves. Those choosing to handle declarations themselves may need to invest in specific software.

Link: Not VAT registered? Don’t forget to apply for your EORI number post Brexit