Can I apply for a TR60 extension any time during my initial 60 days stay in Chiang Mai?

Chiang Mai allows you to apply for an extension when you have 45 days or less left.

They 100% require you to not only have proof of TM30 but once you arrive at the office you'll be sent to convert whatever proof of TM30 you have into their TM30 form.

Usually within the 45 days before the expiration date on your stamped permission to stay is OK at Chiang Mai Thai Immigration. So wait til your first 15+ days have ended... The 30 Day extension of stay is ADDED to your current ending date.

THESE are the common found requirements for the 30 days extension of stay at your local Thai Immigration office for 1900 Thai baht. Be sure you have a TM30 address registration on file with Thai Immigration.

MEMBERS PLEASE NOTE that Chiang Mai Thai Immigration ALLOWS extension of stay applications up to 45 days before your current ending date.

Many other Thai Immigration offices accept applications within 30 days.

And there are several Thai Immigration offices, like Jomtien Immigration, which will Only accept extension applications during the final 7 days of your current ending date.