How many days before my expiration date can I apply for my Non-O retirement extension in Thailand?

You can typically apply for your Non-O retirement extension when you have 30 days or less left before expiration at most immigration offices. However, in some locations like Bangkok, Chiang Mai, and Phuket, this period extends to 45 days. Hua Hin prefers applicants to come in 1 week prior to expiration, while Korat also allows 45 days. It's important to check local practices, as each immigration office may have different preferences.