1. Go into the customer detail.
2. Click the Defaults button.
3. Click New.
4. Click the Selected Default elipsis button […].
5. Scroll down and click on the Usual VAT Code line and then click the Select button.
6. Click the Selected Value elipsis, click on the Zero Rated line and click Select.
7. Click Save at the bottom of the window and then click Close.
8. Close the other windows as required.
That customer is then set as zero rated. It will come into effect immediately but will not affect any previous invoices.