VATTOS3700 - Identifying a tax point: exempt and zero-rated supplies
It is important to remember that tax points apply to more than just positive rated supplies. They apply equally to exempt and zero-rated supplies with one exception. It follows that, because an invoice issued in respect of a supply that is not subject to VAT is not a VAT invoice, invoices only create a tax point for positive rated supplies. For further information see VATTOS5210.
So, for a single supply, say, of exempt services the time of supply will normally be the earlier of receipt of payment or performance of the service. Similarly, the tax point for, say, a zero- rated supply of goods will normally be the earlier of receipt of payment or the removal/making available of those goods.