I guess with personal imports these tariffs will be handled the same way as they do with import taxes. It will depend on the store you buy from to whom you will pay this tariff. I live in the EU and when I buy an item from a store outside the EU there are 2 possibilities;
1) the store is IOSS certified and they can charge me for all Dutch import costs and sales taxes. The sales price of this store is including all additional costs. The store will settle these import costs and sales taxes with Dutch tax authorities,
2) the store is not IOSS certified so they can’t settle these import costs and sales taxes with Dutch tax authorities. When my purchase arrives in the Netherlands, Dutch Customs will charge me these import costs and sales taxes.
Only way to lower the paid tariff might be buying from a foreign store who is prepared to cheat with the price mentioned on the customs declaration. This might sound attractive however it can bite you in the back when your purchase get lost in the mail. An insurance will only compensate for the price mentioned on the custom declaration. As cheating with these customs declaration is considered a fraude, once discovered it can bring you into big problems with your tax authorities……..