You need a B211A visa if:
1) You plan to stay longer than 60 days in Indonesia.
2) You are not sure how long you want to stay in Indonesia and you want to maintain the possibility to stay longer than 60 days without having to leave the country.
3) After arriving in Indonesia, you want to apply for a temporary residence permit/KITAS (investor, spouse, retirement…)
4) Your reason for entry is not for tourism purposes (e.g. business, family, education)
7) You stay longer than 30 days in Indonesia, plan to travel a lot during your stay and might be unable to come to the Immigration Office for your visa extension (you must come in person for your photo and fingerprint visit).
8) You have only a temporary passport and want to enter Indonesia.
9) It is uncertain whether a visa on arrival will be granted due to your vaccination status or other formalities and you want to be on the safe side.