When the invoices for a specific (or multiple) VAT period are required, follow these steps to retrieve all invoices for that period.
Click on the search box with 'Choose Tag' in it.
A drop down menu automatically appears with the available tags:
Select the required tag. Multiple tags can be selected by repeating the process
All invoices with that tag are now displayed with a grey tag icon showing what tag they belong to:
To Download these invoices into one excel file see here.