The purpose of a tax group list is that you can specify different tax rates that are selected using the customer's country. You must as a minimum create one tax group list that is used as the standard tax. You can find the tax group lists in the menu Settings -> Finance -> Tax Group Lists.
Enter a name for the tax group list that is used internally within the administration program.
Check the tax group list that should be used as the default list.
Here you can add the tax groups by priority. The tax applied for a customer will be chosen by country.