Taiwan launched the Fall-Winter Covid-19 Prevention Program: Board Quarantine from Dec.1st, 2020 ~ February 28th, 2021.
A Covid-19 RT-PCR test result certificate issued within 3 days is required prior to boarding the flight to enter/transfer in Taiwan. https://www.cdc.gov.tw/File/Get/E68loEjHOrbk9xujvoHJPQ
Fall-Winter COVID-19 Prevention Program FAQs concerning RT-PCR test result reports issued within 3 days of boarding.
Travelers who cannot present COVID-19 RT-PCR test reports prior to boarding
From Dec. 1st. 2020, must wearing masks in these 8 types of public venues in Taiwan :