If you are on the original 90 days you can stay till the end of it.

IF you are on a 1 yr extension, the day you stopped working that is the end of the extension.

You are NOT able to stay to the end.

You absolutely can convert to a 90 day non-o in country as long as you have enough time left on your stamp.

It is a 5 year visa. You only have to prove the qualifications the first time.

As long as you leave and return every 6 mos. no problems.

If you try and extend in country you will likely have to prove finances etc. again.

I would say option 3 go for a soft power.

Cooking, muay thai etc.

Avoid the complicated.

@Marcus *******

every entry is at the discretion of the officer you are in front of.

Regardless of what visa, it doesn't happen often but it does happen.

@Jurgen *******

you would not want an OA as all extension of that visa will require health insurance always.

You would also require the funds in a Thai bank, same as the non-o.

If you are going to extend in Thailand then OA doesn't make any sense.

IF you go OA you could stretch it almost 2 years if you leave and return just before it expires, as each entry gives you 1 yr. before the expiry.

You can apply for the 1yr extension at the earliest (some offices) 45 days or 30 days left on your 90 day.

You need to find out at the immigration office local to you.

If you do not qualify and things are being "handled" then you have to pay exorbitant amounts.

So the obvious question of the OP is do you qualify, money in bank etc. Or is the agent "fixing" it?

If you qualify yes it's fairly simple.

The rule has always been the same.

They have discussed implementing/enforcing taxation on tax residents of 180 days plus.

However no official procedure is implemented yet.

Anyone registering is doing so voluntarily and they do not have the system in place yet to process.

It is a wait and see at this point what , if anything , comes of it.

They are after those hiding global income, many rich Thais and foreigners with overseas money taking advantage of a loophole that is supposedly closed now.

Money being brought in , may be subject to tax regardless of whether it is not in the same fiscal year.

If you send a flight from Indonesia they will likely cancel it as you are supposed to be in the country you applied.