According to the "National Health Insurance Act, Enforcement Rules of the National Health Insurance Act," foreigners should enroll in National Health Insurance upon completing six full months of staying in Taiwan after obtaining their Alien Resident Certificate (ARC).
※"staying for six full months" meaning the person has stayed in Taiwan for six consecutive months after entering into Taiwan with residency or exited Taiwan once for fewer than 30 days with the actual period of stay amounting to six months after the number of days that he or she has been away from Taiwan is deducted.