The official rules for extending any type of visa, such as non-O, non-B, visa and education visas are written in the next documents:

ORDER OF THE ROYAL THAI POLICE No. 777/2551 Subject: Criteria and Conditions for Consideration of an Alien’s Application for a Temporary Stay in the Kingdom of Thailand


ORDER OF THE IMMIGRATION BUREAU No. 305/2551 Subjext: List of Supporting Documents for Consideration of an Alien’s Application for a Temporary Stay in the Kingdom of Thailand
These documents can be downloaded at the website of the Immigration Bureau.

http://www.immigration.go.th/nov2004...77-2551_en.pdf

http://www.immigration.go.th/nov2004/doc/temporarystay/policy305-2551_en.pdf

Translated by Tilleke & Gibbins. Revised by Legal Div. Royal Thai Police Headquarters ©2009 Tilleke & Gibbins International Ltd. All rights reserved.