The supply of goods exported from the UK is zero rated as long as certain conditions are met.  One of those conditions is holding evidence that the goods have actually left the UK.

The declaration of exports is now largely handled through the Customs Declaration Service (CDS) and soon all exports will have to be declared using this system.

Under the previous system the official evidence that the goods had left the UK was the Goods Departed Message (GDM) . Under CDS there are no Goods Departed Messages and therefore you must keep a copy of the CDS export declaration if you are relying on official evidence.  You can also use commercial evidence to provide proof of export but this can be difficult to obtain.  Types of acceptable commercial evidence are set out in VAT Notice 703.

If you do not keep acceptable evidence of export the goods revert to their normal UK VAT liability, so it is essential that you have systems in place to capture and keep adequate evidence of export.