What are the latest and minimum days remaining for extending a 90-day NON-O retirement visa in Thailand?

To extend a 90-day Non-O (retirement) visa for one year in Bangkok, you can apply as early as 45 days before your current visa expires. The latest date to apply for the extension would typically be the date of expiration, as you generally need to have some valid days remaining on the visa. It's advisable to apply well ahead of expiration to avoid any potential issues.