Printful charges you VAT for orders that are fulfilled at our Europe location with an end-address in an EU member state.
You need to collect VAT on orders that have an end-destination in the EU, regardless of where they're fulfilled.
This is the formula you should use to collect VAT:
(Your retail price + shipping - discounts)*VAT rate %.
The VAT rate percentage depends on the country that you're registered in. Take a look at each country's VAT rates here.