There have been so many misleading/conflicting links posted on this ongoing saga that I asked you to provide a specific link to substantiate your specific point "The tax law says that anyone with assessable income of THB 120,000 per year or more, must file a return."
The post above does not make that statement!
You have still failed to provide a link which specifically states, as you claim, that;
"The tax law says that anyone with assessable income of THB 120,000 per year or more, must file a return."
Please provide a SPECIFIC link! (if you can!)