This is information regarding transferring visa and/or visa extension in Chiangmai Immigration office.
After having applied a new passport, I enter the Kingdom with both former and new passport. The papers you need are
1. Form for visa transfer. You can download the form Internet, or request it at the office counter.
2. From your new passport, you need to photocopy the ID page, entry stamp. I included the backside of departure card with the entry stamp.
3. From your old passport, you need to photocopy the ID page, and "every page of your current visa and extension." This is that it means. I am staying in the Kingdom on an extension applied this March and it was based on a visa I used in June 2016. Therefore, I need to photocopy every page from June 2016 to this year.
4. Visa transfer is free.
Bonus point: According immigration officer, you can do TM30 reporting regardless you have transfer your visa or not.