Non-Immigrant O Visa or as most retirees called "Retirement Visa'"
Thailand retirement visa is the popular term for "Extension of Stay Based on Retirement”. It is an extension of a Non-Immigrant O Visa or Non-Immigrant OA Visa.
"Apiporn was great! So patient and attentive with my many questions and excellent advice. Entering Thailand was a breeze thanks to her kind help! You can’t ask for more."