Ok, so this is strange. I decided to go to the Chonburi Immigration office (servicing Pattaya), for a 30 day extension.

They required hotel reservation with some other supporting documentation (business card from the hotel or something). Or you can use a private residence with some other supporting documentation. I had none of these as I was using AirBNB (turns out to be a big no-no).

As I was waiting in line to do the 'check-in' part of the extension, the guy in front of me was saying how once, he had done the same thing. However, because he didn't 'check-in' within 10 days (or some small window) he was fined 1600 Baht.

I didn't stay to complete the process. Based on my limited experience, unless you need to- avoid the Chonburi Immigration Office.

Anybody else agree (or disagree)?