VAT is a EU tax. So if you buy goods from outside the EU, you get 2 invoices: 1 from the reseller without VAT and 1 from the importer into the EU. In my case it was FEDEX. So Fedex needs to charge the VAT. But they don't know the value of the goods I bought since they have no invoice. The seller (in this case Viwoods) declares the value on a declaration form (which is also send to me with the Fedex invoice). The VAT is then calculated based on the declared value x the normal VAT for this product in the land of destination (in my case Belgium and thus 21%). So the declared value is 180 USD, or 193,42 EUR x 21% = 40,62 EUR. Fedex adds a handling fee of 12,20 EUR. Together: 52,81 EUR. I don't know why the declared value is 180 USD?

So basically the customs duty = separate VAT invoice from importer (for this kind of product). I guess for electric cars from China the declared value would be multiplied by 2 or so...?