For Sarah Chang who asked about TM30 and extension of stay at Chiang May, here is the instruction panel at the entrance of immigration: the TM30 seem to be mandatory now. I got my TM30 myself very easily with the proper document filed by the condo manager, but you have to get them from him/her before
TLDR : Answer Summary
The TM30 form appears to be a common requirement for transactions at Chiang Mai Immigration, including the extension of stay; however, there is debate among expats about its necessity specifically for 30-day extensions tied to tourist or visa-exempt entries. While some individuals report being asked for TM30 confirmation during extensions or 90-day reporting, others have successfully obtained extensions without providing the TM30 receipt, indicating a lack of consistency in enforcement. It's advised to seek confirmation from your accommodation (like condos or hotels) if they have completed the TM30 filing online to avoid complications.