I think you might not be too familiar with some aspects of this topic and the language used. I know you only want to be helpful, but you are providing inaccurate information. Let me clear up a few points.
The original poster said he was an “overseas Chinese with an ROC passport without household registration”. “Overseas Chinese” can mean a lot of things, but it very likely means he is of Chinese blood, born in the US/Canada/Australia/UK or some other country outside of China/Taiwan/HK/Macau. In this case we know he has a Taiwanese connection, or he would never have gotten an ROC passport.
However, there is more than one kind of ROC passport. Having an ROC passport WITHOUT household registration means that he is the definition of an overseas Taiwanese. These passports DO NOT have a national ID number (身份证). THAT’S THE ONLY DIFFERENCE. So while he is indeed a Taiwanese national, he does not have the right to just live and work and vote in Taiwan like a Taiwanese person born there does. He does not have full nationality.
To get full nationality rights, he must “reclaim nationality” or get an ID number.
To get that ID number, he must first enter Taiwan on his overseas Taiwanese passport WITH an entry/exit permit (usually valid for 90 days) AND THEN make an application for a TARC.
One year after the TARC is issued (or the time requirement described previously), he can go to the housing authorities REGISTER HIS HOUSEHOLD, and then get this national ID number (which comes on the ID card). THEN he will have FULL nationality rights like other Taiwanese people and can apply for a Taiwanese passport WITH HOUSEHOLD REGISTRATION.
If he has an ROC passport WITHOUT HOUSEHOLD REGISTRATION it is definitely true that he can only apply for the TARC AFTER entering Taiwan on that passport.
I belive that non-Taiwanese who wish to become Taiwanese go through another process to get a TARC, but that’s not what we are talking about here.
I don’t know about the use of ROC entry permits in non-ROC passports, so I can’t comment. But again, this is not relevant to this particular case.
You are definitely right about the 6-month wait on the insurance. However, I have learned that that six months begins AFTER the TARC is issued (and not when the person enters the country).
Taiwanese immigration is very complicated and there is a not a lot of good information out there. Even the people at TECO don’t always have the right information. I had to learn this stuff by myself, going through all of the procedures. This meant many, many trips to the immigration office, getting piles and piles of documents translated, notarized and authenticated, lots of phone calls to my family in the US, having my mother come to Taipei to update her information, taking bad advice from well-meaning people who just don’t know what they are talking about, and waiting and waiting and waiting for answers to what seem be simple questions but are not.
And I was in a very similar situation to the original poster–I was a Taiwanese national without household registration.
It’s very important to try to leave accurate information for others looking to go through this process themselves. If you are not very knowledgeable about the details of these specific cases, it’s best to refrain from clouding the issue.