How many days before my retirement visa extension expires can I apply for renewal in Thailand?

You can apply for a renewal of your retirement visa extension either 30 days or 45 days before the current stamp expires, depending on the immigration office location. In places like Chiang Mai, Bangkok, Buriram, and Phuket, the timeframe is 45 days, whereas in most other areas, it is 30 days. It's advised to check with your local immigration office for specific rules.