Can I purchase a new training block at a gym in Koh Samui for my DTV visa re-entry?

You're fine for re-entry - you don't need new proof to get back in.

*DTV is not tied to that one Chiang Mai gym expiring.*

Your DTV is a 5 year visa. Once issued, immigration at BKK / Samui Airport does NOT check if you finished your 6 month course. They see valid DTV, they stamp 180 days. No one at border asks for gym letter on return - that's only for extension at immigration inside Thailand.

So for your flight back to Samui: just DTV eVisa + TDAC. You're good.

*Where you do need proof:*

1. If you want to extend your 180 day stamp to +180 days at Koh Samui Immigration (for 360 days total per entry) - they WILL ask for ongoing training proof. An expired Chiang Mai course won't work.

2. If you apply for a new DTV in 5 years.

*For your situation - moving to Samui:*

Yes, buying a new block from a legit gym in Samui is perfect and what most people do:

- Get 6 month or 12 month course paper - with gym license, curriculum, your name, dates covering your next stay

- Keep receipts + training photos / attendance - Samui Immigration actually checks attendance logs now for Muay Thai extensions

- Don't need to cancel old gym, just start new one

Chiang Mai course expired after 3 months you left - that's normal, no penalty, no blacklist. Thai gyms don't report non-attendance to MFA.

You could consider reading a book or two before your trip. I’d recommend Unlock Thailand by Isla Rey on Amazon, it includes all the info and insights you need. You should check it out. A very good companion 👌.

Depends totally on the Immigration Officer that review your documents.

You didn’t live up to the reason you gave for getting the visa, why should the IO believe that you will do what you are expected to do next time, when you didn’t live up to the terms and conditions of the visa, during your first stay.

Book for the new school before you leave. Keep the payment recipe. At least that is what other people in other questions answered and claim to successfully have done.

This visa is made to make sure you integrate the culture, just make sure you take lots of videos everytime and keep an instagram just for muay thai as a proof where you post videos once a week/every 2 weeks (even old ones). Also keep receipts of payments. As long as you train a bit you're fine. When you re-entry just book your gym in advance, take with you a Fairtex bag and put gloves in your bag and say you're here for muay thai, don't talk about traveling or whatever other plans you have. If they ask more, show the receipt of the booking for your gym. You will be fine.

Is the school accepted by the DTV ??

Nothing I have seen posted means you are tied to the original gym. Go for it. The majority entering have zero booked after first booked course finished although it was an issue for one entrant this week.