I’ve received a response from them:
Regarding your incorrect withholding statement for a bank account, there is no way to tell the bank to correct your incorrect withholding statement.
The bank can not judge whether your are resident or non-resident during the whole year beause they can not access your entry and depart records.
Don’t worry. When you file your tax return. we will calculate the correct tax payable amout. If the bank withheld the wrong withholding tax, we will get you tax refund or decuct your tax amount.
I hope it will solve your problem.
What I understand from that is that the tax office basically agrees with the banks that the resident status of foreigners (regarding Taiwan) has to be determined every year based on entry records…