I'm changing employer soon. I hear that the WP is actually transferable. Can anyone clarify, or perhaps post a link for my perusal?

Many thanks

A Work Permit is not transferable. You should seek advice from Sunbelt or Indo Siam. Wp's are their sphere of expertise.

You have to turn the old work permit in, if you are no longer working for that company. Simply apply at the new company.

You can however work for two companies at the same time with one work permit. IT MUST be approved by the Thai authorities and noted in your work permit book.

Then do you need to earn more than 60KTHB for each company ... or in total ?

Its still 40K max for each company. It will raise soon as you note for the Japanese and Americans to 60K.

If you are volunteer, then of course the second requirement of 40 or 60K would not apply.