Question about health insurance for students

I always thought that every foreigner in Taiwan with an ARC is entitled for the national health insurance after 4 months. I even thought that it was compulsory.

Now a friend of mine who studies at Ching-Yi in Taichung has got the ARC, and has been in Taiwan more than 4 months. However, he can’t get the health insurance. Why? Because his mother is very ill and he has been back home a couple of times so that he wasn’t in Taiwan for four months uninterruptedly since he has got his ARC. How could they tell? Because he has go one of the new machine readable ARCs. Really crap, init?

Does anybody know the details of the regulations regarding health insurance for ARC holders?

Anyone?