Should I renew my non-immigrant O visa before leaving Thailand or start over upon returning?

You can go to renew your visa 45 days in advance. If you do a new visa, you will unnecessarily lose a lot of time and energy.

If I read all correctly. (Wink) yes. My personal experience. Can do 90 days before month your visa expires

Which non-o ?? If you are talking retirement visa you dont need the money in savings if you were able to move over the min required amount each month - it still shocks me that people think the savings is the only way to go

I would extend or renew in country provided you were able to make the minimum deposit every month 75,000 thb - you dont need to have the 800k in savings there are 3 options

Savings

Income/savings

Income

If you use an agent then you actually never learn how to do what is relatively simple to DIY, plus it costs you baht every time that you could have spent on something else. Plus there are some agents who make mistakes either by accident or on purpose whilst immigration will hold you liable. I think they probably do not have any regulatory body overseeing any professionsl standards or carry any indemnity type insurance cover. If a job's worth doing, it's worth doing yourself. Just keep upto date looking out for any changes. Bangkok Bank changed their rule to say the 800,000 must be in your account for 4 months before renewal, not 3 months like most other banks. They also didn't tell their customers, which was kind of them. They can refuse to write your confirmation letter.

Go n get the right visa to stay long term .

Best option, keep ya coin and start afresh when you’re ready to return.

As already mentioned, it depends on what 'visa' or extension you have. If it's a non-immigrant O visa with a retirement extension then you will have needed to have the 800k in the bank for 3 months prior to applying plus have had 400k for the rest of the year, unless they have changed the rules. There had been instances of agents putting the 800k in the bank, getting the extension of stay and then immediately taking the money out and this is most likely why some banks are now locking accounts for 3 months after issuing the letter for immigration so if you previously used an agent you might not be able to do so in the future. I would check with immigration for your exact requirements.

If your plan is to do the extentions yourself for possibe "many years" I would start over obtaining a new 90 day visa

I would leave and obtain a new 90 day visa before returning to Thailand 🇹🇭. Put the 0 baht in your bank and extend for a year. Putting 0 bhat in your account now and trying to extend yourself might draw attention to the fact that you did not meet the terms of your last extension. Starting afresh could save you a lot of trouble and money if you do it yourself.

You don't actually have a visa but an extension of stay so it will depend on the type of extension of stay you have. If it's based on marriage it won't work with your dates due to the under consideration period. If it's based on retirement, which I'm going to assume it is, did you meet the criteria of having 800k baht in your bank account for the first 3 months of the current extension and never going below 400k at any point in the year? If not your probably going to have to use an agent again as you haven't met the requirements of your current extension, which likely means you won't be able to do it yourself. As to timing, it depends where you are, all immigration offices will allow you to apply when you are down to 30 days or less on your current stamp, a few of the larger ones will allow you to apply when down to the last 45 days