How early can I apply for my yearly R-A visa extension before the expiration date?

In Thailand, the timeframe for applying for a yearly R-A visa extension varies by immigration office. Most offices allow applications to be submitted 30 days prior to the expiration date. However, in some regions like Bangkok and Chiang Mai, applications can be accepted as early as 45 days before the due date. Phuket also follows the 45 days rule.