How to get the most time in-country out of a year-long, multi-entry Non-Immigrant Type O-A (Long Stay) "retirement" visa.
First off this information is ONLY about the Non-Immigrant Type O-A visa that you get from a thai consulate in your country BEFORE you come here. This is the visa that requires you to be over 50 y/o, needs a police background check, a medical certificate and meeting the financial requirements of 800K baht (or the equivalent) in a bank in your country.
The visa is valid for a year from the date it's issued AND every time you enter thailand during the validity of the visa you are stamped in for a completely new year.
The way to get the most time in country out of this visa is to get it as close to the time you're comin' to thailand as you can. Because the visa is valid for a year from the date it's issued you don't want to get it too early and then burn up the validity NOT being here ;)
Once you arrive you're stamped in for a whole year. During the validity of the visa you can exit/re-enter the country all you want and you will be stamped in for a completely new year each time.
However keep in mind when the visa itself expires. You need to exit/re-enter the country one final time just prior to the "enter before" or "valid until" date on the visa itself. That will get you stamped in for a new year (in essense giving you TWO years of stay out of a one year visa.
Remember also, IF you exit the country AFTER the "enter before" or "valid until" date on the visa itself you will need a re-entry permit to get stamped back in on the remainder of your last entry stamp because the multiple entry part of the O-A visa expires on the "enter before" or "valid until" date.
This is an example of a year-long, multi-entry Non-Immigrant Type O-A (Long Stay) "retirement" visa.
You can see it is an O-A visa, has Multiple entries, was issued Oct 4th 2017 and has an "enter before" date of 3 Oct 2018. When the holder of this visa enters thailand they will be stamped in for a full year. AND as long as they exit/re-enter thailand one final time just prior to 3 Oct 2018 they will be stamped in until Oct 2019 (another full year).
Sorry this was long, hopefully it was helpful ;)