How many days before the expiration of a Non-O visa can you apply for a 1-year extension in Thailand?

The timeframe for applying for a 1-year extension on a Non-O visa in Thailand varies by province. Some immigration offices accept applications up to 45 days before the visa expiration date, while others require applications to be made 30 days in advance. For example, in Phuket, you can apply 45 days prior, whereas places like Jomtien and Buri Ram only allow 30 days.