To be clear, the two types of 'tax' that might be payable on imports from China are 1) VAT and 2) Import Duty.
VAT is (with very few exceptions) is always payable at 20% of the value of product plus freight.
Import Duty is payable if the Tariff for the product requires it. The Tariff varies product by product, country to country. To find out what the Tariff's are, look here:-