What is the current process for obtaining a retirement visa in Chiang Mai, Thailand, and how can I include my dependents?

Just to emphasise what

@Brandon ***********

said. If you are on a Non-O based on retirement your wife (and probably child) will NOT be able to get a Non-O visa as your dependant inside of Thailand, nor in any nearby country. She might be able to get one in your home country but you don't say where that is, but it's more likely they would require you to be on a Non-OA visa for that although she might also be able to get one in your home country once you are on a 12 month extension of stay. Really you need to talk to the Thai embassy in your home country about the possibilities.

You can apply any time you want to convert from visa exempt to non-O, but must have at least 21 days left on your entry stamp.

You cannot apply for extension after 30 days. You would need to wait at least 45 because in Chiang Mai you can only apply for extension during your last 45 days.

Make sure you're aware if you have Bangkok Bank that if the money you're going to use for visa/extension has not been in your account for 4 months already on the day you ask for the bank letter, they'll require you to sign something freezing your funds for 4 months from the date the letter is issued. All funds in the bank at that time will be frozen for 4 months.

Getting the visa from home saves you at least 2 trips to immigration. The first trip to apply for conversion and the 2nd trip to pick up the visa stamp after the under consideration period.

Also if you're applying for non-O based on retirement you must be able to show the funds in your bank came from overseas when applying in country. This is not the case for the extension.

NOTE: No immigration office in Thailand allows you to apply for trailing spouse visa. You will not be able to get a non-O visa for your foreign wife based on your visa. She'll have to qualify for her own visa. I don't know of any embassies in the world that still allow for this either if you have a non-O visa. Some do still allow it if you get a non-OA visa. But then you have the insurance requirement.