Taiwan’s arrival card is submitted online through the National Immigration Agency before you travel.
Submission is free of charge. As with every arrival card in the region, that is worth stating plainly, because paid intermediaries exist for forms that cost nothing.
Timing
Submit no earlier than seven days before arrival. Earlier than that and the window has not opened yet.
What you need to hand
A valid passport, the traveler’s email address, occupation and phone number, and your travel and accommodation details.
Gathering those before you start is faster than discovering halfway through that you do not know the hotel address.
Who does not need one
Foreign nationals holding an Alien Resident Certificate, a Resident Visa, or a Diplomatic Identification Card are exempt.
Who does need one, and might not expect to
Travelers from mainland China holding a Multiple Entry and Exit Permit for tourism are required to submit an arrival card.
So are Hong Kong and Macau travelers holding a Multiple Entry and Exit Permit. Holding a multiple entry permit does not remove the arrival card requirement.