When setting up a Taiwanese address on Amazon, they require a 10 digit ID number with one letter and 9 numbers:
Packages will not clear customs without the recipient’s valid ID Number. We do not use this information for any other purpose other than customs clearance.
Please enter the 10 character ID Number of the recipient. It consists of 1 alphabet and 9 numeric digits.
My ID number has 2 letters and 8 numbers. What am I supposed to put?
Also how much is the sales tax, and how do you pay it? Does the courier ring you and ask for a credit card number?
TL;DR; Amazon will complain about ARC IDs but will accept them anyway.
This is because you have an ARC ID which always have a C on a second place for Alien Resident. Usually there is a number which represents gender. This often creates problems as a lot of software implementations that do ID number validation do not consider ARC IDs, which by the way is illegal because of anti-discrimination laws.
A valid National Identification number consists of one letter and nine-digits. The initial letter depends on the place of one’s first household registration. The first digit depends on gender; 1 for male, 2 for female.
A workaround exists which lets your ID validate in cases where they fail to accept a valid ARC ID. Replace the C in the second place with a 2.