Can I apply for an extension of stay in Thailand based on retirement up to 35 days before the due date?

Yes, it is possible to apply for the extension of stay in Thailand based on retirement up to 35 days in advance of your current visa's expiration. The specifics can vary by location; for example, offices in Bangkok and Chiang Mai allow applications when there are 45 days or less remaining, while other offices may allow it at 30 days or less. It's important to note that the new extension will start from the original due date.