@Wyn *********
how about you look at the OA visa sticker in your passport and tell us with the valid until or admitted until date is on it? (it's a year from the date it was issued).
The entry stamp you get off it is totally irrelevant.
IF the expiration date on the visa STICKER has not passed yet and you can get out and back before it does you will be stamped in for another year (or as long as you have the mandatory health insurance)
BUT
if it has past already you're allowed to be here until your current entry stamp expires. <- at that point your entry stamp does become relevant 😛
AND
if you're going to get an extension of stay from the immigration office for 1900baht you need to have 800K baht in a thai bank account in your name only for 2 months before you apply for the year extension
You're also going to have to have another year of the mandatory health insurance with one of the 14 approved thai OA insurance carriers
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