I have a health insurance card with a short expiry date. Why.

The insurance card is renewed once every two years on October 1st, so it is valid until September 30th.
Cases in which an insurance card with a short expiration date is issued are as follows.
(1) If you will be 75 years old by September 30th, you will be transitioning to the Medical Care System for the Advanced Elderly from your 75th birthday, so the expiration date will be the day before your birthday.
(2) If you fail to pay the National Health Insurance tax and do not respond to demand or tax consultation, we will issue an insurance card with a short expiration date (short-term insurance card). Households that have been issued a short-term insurance card may need to renew it each time it expires.
(3) For foreign residents, the expiration date is the same as the expiration date of the residence card. If your residence card is renewed, you can get a new insurance card issued at the city hall or branch office (Hirao/Wakabadai). In that case, please bring your new residence card.
(4) For those who are covered by the retiree medical care system, the expiration date of the health insurance card may be shortened due to the termination of the system. A new health insurance card will be mailed later in the month in which it expires. However, this does not apply to cases that fall under (2) above.