Is it 100% sure that if I go to get my 30 extension on my 30 day exemption the new 30 days will start on the date that was stamped in my passport? (Entered on Nov. 22, given until Dec. 21st) I am in Phuket. Thanks in advance! Only asking because someone said the new 30 days would start the day I apply, which is not what I've been seeing here.
TLDR : Answer Summary
When applying for a 30-day extension on your 30-day visa exemption in Thailand, the new 30-day period is added to the original expiry date stamped in your passport, not the date of application. For example, if your original stay duration is until December 21st, your new expiry date will be January 20th.