@Matts ************

some immigration offices will not accept joint bank accounts at all.

For visa needs, you would need your own account. Also joint accounts don't provide any benefits because only one person can ever have that account accessible via the bank's phone application.

Just find a teledoc or something. Most doctors know it's a joke and will sign it. Your doctor is being unreasonable.

@Lisa ******************

under 20 means under 20. 19 is the cutoff.

As far as kids attending school, that's not relevant. You don't need any specific visa to attend school. Anyone can attend school on any visa.

@Stephen ********

yes there is. But it's a little different there. You have to get stamped out or go through the automated exit gate first, and then loop back around to the re-entry desk. Just ask an immigration officer if you need assistance on locating it.

It's called an extension of stay. But you don't say what type of non-O you will have so it's impossible to advise what paperwork might be required. You'll need to go to your immigration office and ask them for a handout of their requirements because each immigration office is different.

You would need to purchase a re-entry permit if you want to leave without your entry stamp being cancelled. But you need to make sure you get your bank account opened and funded with the required money within your first month, because if you don't then you will not have enough time to apply for the 1-year extension. The money must be in your account already for 2 full months at the time you apply. Since you'll only have 90 days, that means if you don't get the money in place in the first month, you can't apply for the extension.

They want to see the statements. So unless you plan on blacking out everything except the final balance, then no.

Can you even sponsor him when he's 20? That's the age of adulthood in Thailand, so I'm not sure if they would even allow it already.

I've only seen reports of Chiang Mai being difficult if it's someone's very first entry in Thailand on a DTV. You said "back into" so it doesn't seem like it was your first entry.