In Better Clinics, you have an option to create your invoice as 'Tax Invoice'.
Or go to Settings > Add Location (Subcategory of 'Locations')
The right side of the page is for Invoice Settings. Use the tick boxes to determine what fields you want to be displayed on your invoice. Option for 'Invoice Title' has a dropdown and you can choose to have a Tax Invoice.
Click Preview Invoice to download the copy of the Tax Invoice.