I think this was just rookie mistake. You probably did not read though the ‘fine print’ / shipping info page at the bottom of the website. It clearly says that shipping fee will be included in the customs calculation. It also mentions “rewards” being calculated as well but I think that is if you use ‘Rewards Credit’ to reduce the price.
You should have just used the free shipping option that might take a few days longer. However, even then, you still ‘probably’ would get hit with duty. You really need to stay under NT2000. Once you go over, the duty is for the entire order. They don’t exempt the first NT2000 and only calculate on the balance value.
You can make multiple shipments of under NT2000 for free shipping and free duty but I remember that if you make too many within a 3 or 6 month period after that they will start charging you.
Supplements will have a higher duty compared to food items. I just use Costco for most stuff these days but I do iherb about 3 times a year and always under NT 2000 and never had an issue.
copied and pasted from iHERB.
Orders over USD $65.00 (NTD 2,000) may be subject to D&T.
Rewards will be included in the Customs tax and duty calculation along with the shipping fee.
Placing multiple orders within a short period of time can cause customs clearance and order release delays.
For information about customs, import duties, etc., visit: Customs Administration
Taiwan Customs may require you to submit additional documentation for the custom clearance, including without limitation: Copy of Identification Card and Power of Attorney. Failure to provide required documentation may result in customs clearance delay or rejection.
According to the recent policy of the Taiwan Customs Administration, it is mandatory for consignee to go through real-name authentication. Otherwise, shipment will be held in Customs.