The National Health Insurance program is to ensure that everyone enjoyed equal rights to healthcare, including people without health insurance protection prior to the system's inception, such as dependents, veterans, and the unemployed, including housewives, students, children, and the elderly. All of residents have equal rights to access medical services when they get sick, are injured, or give birth. Based on this framework, all nationals of Taiwan with a registered domicile for six months or more, and all infants born in Taiwan, must participate in the NHI program. There are six categories of insureds, which provide the basis for the calculation of insurance premiums.

     In line with recent societal changes and in consideration of human rights and the principle of fairness, the NHI system has been revised several times over the years. Coverage has gradually expanded to include new immigrant residents, foreign nationals residing in Taiwan, overseas Chinese and foreign students, and military personnel. Through the implementation of second-generation National Health Insurance, inmates at correctional facilities have also been included in the system to ensure their right to medical care. Overseas Taiwan nationals who returned Taiwan and re-established household registrations must enroll in the program if they enrolled in the NHI within recent two years or have established residency in Taiwan for at least six months. Foreigners with an Alien Resident Certificate (ARC) have resided in Taiwan for at least six months must also enroll in.