Since the United Kingdom’s (UK) exit from the European Union (EU) on 31 December 2020 (end of the transition period) the rules on sending good to and from the EU have changed. You will now need to fill out customs forms when sending goods to the EU, unless sending from Northern Ireland.
A brief note on Northern Ireland: It has remained in the EU’s single market for goods to prevent hardening the border between Northern Ireland and the Republic of Ireland, which is an EU country. This means that in several ways Northern Ireland will be treated as though it is in the EU, even though it is part of the United Kingdom which is no longer in the EU. It means goods arriving from Great Britain are now meant to be checked and controlled at Northern Irelands ports similar to sending goods to the EU. Some goods that enter Northern Ireland from Great Britain could be subject to additional costs. To take your pet dog to Northern Ireland you will have to go through the same process as taking your dog to the EU.
When sending goods from Great Britain (England, Scotland, and Wales) to the EU you will need to fill out one of two forms. For items worth up to £270 it is customs declaration form CN22 and for items worth over £270 it is customs declaration form CN23. The forms should be attached to the parcel using a plastic wallet available from the Post Office. You will not need to fill out either form when sending personal correspondence.
When receiving good from the EU, the goods will now be treated in the same way as receiving goods from non-EU countries. For the import of most goods not exceeding £135 the point at which VAT is collected will mostly be at the point of sale rather than the point of importation making it UK supply VAT instead of import VAT. Shipments exceeding £135 in value will be subject to existing customs rules and processes.