How can I activate tax codes on my account with 0%?

Hello Kathryn9, 

Thanks for reaching out to the community page, 

If you go to the taxes page>edit vat>edit rates> make sure all the tax rates are turned on there that you need. Once there are turned on you will be able to select the for example the 0% for the transaction you are doing.  Let us know if you have any issues.