- Make sure you've uploaded the CartThrob themes folder to
your_site_root > themes > third_party > cartthrob
To make sure that the settings javascript is available (the settings don't work correctly if it's not uploaded)
- cartthrob settings > global > default location
set your default country to the Netherlands (or other country as needed). This way CT will assume that anyone visiting is starting from the Netherlands, even if they are not logged in, and there is no default location data to work with.
- Go to cartthrob settings > taxes > tax by location - percentage (i'm assuming this will work for VAT. CT doesn't include a VAT specific tax plugin, but typically it's about 20% so this will probably work fine). It should allow you to select most any country if used with its default locales data. Set a name, % and the country. Add an additional rate beneath that to set a global rate for all other locations (if different)